[OnePlus 6T  Questions & Answers] Boni2k:
Findings:

happened to me when I wanted to switch to Portrait mode within stock camera app.

Logcat, though I did not find anything relevant:

2018-11-11 17:32:24.939 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:24.939 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:1!"
2018-11-11 17:32:24.939 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:24.939 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:1!"
2018-11-11 17:32:24.965 709-1426/? D/CHIUSECASE: [chi_initialize_override_session][221] "[OP_EXT] CREATE_SESSION X"
2018-11-11 17:32:24.966 948-30352/? E/Camera3-Device: configureStreams: Stream 1: DataSpace override not allowed for format 0x21
2018-11-11 17:32:24.966 948-30352/? E/Camera3-Device: configureStreams: Stream 2: DataSpace override not allowed for format 0x21
2018-11-11 17:32:24.978 948-30352/? D/Camera3-Device: Set real time priority for request queue thread (tid 3240)
2018-11-11 17:32:25.005 6421-2742/? W/CameraImpl: startCaptureSession() - Wait for capture session [start]
2018-11-11 17:32:25.016 6421-2831/? W/CameraImpl: Capture session configured
2018-11-11 17:32:25.016 6421-2742/? W/CameraImpl: startCaptureSession() - Wait for capture session [end]
2018-11-11 17:32:25.016 6421-2831/? W/CameraImpl: Capture session ready
2018-11-11 17:32:25.016 6421-2742/? W/CameraImpl: onCaptureSessionConfigured()
2018-11-11 17:32:25.018 6421-2742/? W/CameraImpl: startPreviewRequest() - Start preview request for camera '3'
2018-11-11 17:32:25.018 6421-2742/? V/CameraImpl: startPreviewRequestDirectly()
2018-11-11 17:32:25.060 6421-2742/? V/CameraImpl: cancelAutoFocus()
2018-11-11 17:32:25.080 709-1426/? E/libc: Access denied finding property "persist.opcamera.supernight"
2018-11-11 17:32:25.080 709-1426/? D/OP_META: [SetBracketModeConfig][404] "SetBracketModeConfig BracketMode:0 fwk_iso:0 fwk_exptime:0.000000 MotionDetected:0 hsDetected:0 isHDRCapture:0 m_CameraId:3 " "fwk_SceneMode:0 isflashsnapshot:0, drc_gain:0.000000, fwk_drcIso:0, eagleEyeDetected:0 GyroFromAP:0.000000 is_motion_detect_enabled:0" "is_static_mode_enabled:0 ROICount:0 m_isNightMode:0 fwk_SceneMode:0 face w:0 SquareMotionDetected:0 GreenRatio:0.000000" "luxIndex:0.000000"
2018-11-11 17:32:25.074 709-709/? W/HwBinder:709_2: type=1400 audit(0.0:444616): avc: denied { read } for name="u:object_r:default_prop:s0" dev="tmpfs" ino=17874 scontext=u:r:hal_camera_default:s0 tcontext=u:object_r:default_prop:s0 tclass=file permissive=0
2018-11-11 17:32:25.081 709-1426/? D/OP_META: [AdjustFeature][1493] "AdjustFeature FeatureType:3, isMultiframe:0, isAeBracket:0, m_forceHDR:0, lastFeature:5"
2018-11-11 17:32:25.095 6421-2742/? D/CameraImpl: [Property] PreviewState(id=298) : STARTING -> STARTED
2018-11-11 17:32:25.095 6421-2742/? D/CameraThread: [Property] CameraPreviewState(id=77) : STARTING -> STARTED
2018-11-11 17:32:25.095 6421-2742/? D/CameraThread: [Property] PhotoCaptureState(id=86) : PREPARING -> READY
2018-11-11 17:32:25.095 6421-2742/? W/CameraImpl: startPreviewRequest() - Start preview request for camera '3'
2018-11-11 17:32:25.095 6421-2742/? V/CameraImpl: startPreviewRequestDirectly()
2018-11-11 17:32:25.095 6421-2742/? V/CameraImpl: cancelAutoFocus()
2018-11-11 17:32:25.097 6421-6421/? D/OPCameraActivity: [Property] CameraPreviewState(id=29) : STARTING -> STARTED
2018-11-11 17:32:25.098 6421-6421/? D/CaptureModeBottomSheet: PROP_CAMERA_PREVIEW_STATE changed oldValue: STARTING new: STARTED m_IsSwitchingCaptureMode: false
2018-11-11 17:32:25.098 6421-6421/? D/CaptureModeBottomSheet: PROP_CAMERA_PREVIEW_STATE animationState: m_ContainerAnimationState: IDLE
2018-11-11 17:32:25.126 709-3279/? E/CamX: [ERROR][HAL ] camxmetadatapool.cpp:1434 GetMetadataByTag() Invalid Slot to get a metadata from
2018-11-11 17:32:25.126 709-3279/? E/CamX: [ERROR][PPROC ] camxbpsnode.cpp:756 GetSensorModeData() Mode index vendor tag not provided! Using default 0!
2018-11-11 17:32:25.126 709-3279/? E/CamX: [ERROR][HAL ] camxmetadatapool.cpp:1434 GetMetadataByTag() Invalid Slot to get a metadata from
2018-11-11 17:32:25.126 709-3279/? E/CamX: [ERROR][PPROC ] camxbpsnode.cpp:756 GetSensorModeData() Mode index vendor tag not provided! Using default 0!
2018-11-11 17:32:25.131 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:25.131 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:1!"
2018-11-11 17:32:25.133 6421-6421/? W/OPCameraActivity: onCameraPreviewStarted()
2018-11-11 17:32:25.145 709-3279/? D/OnePlus_Interface: [op_intf][34] ": E"
2018-11-11 17:32:25.146 709-3279/? D/OnePlus_Interface: [init_extra_file][145] ": E"
2018-11-11 17:32:25.153 709-3279/? I/OPAllocator: module_allocator
2018-11-11 17:32:25.144 709-709/? W/HwBinder:709_2: type=1400 audit(0.0:444617): avc: denied { read } for name="u:object_r:default_prop:s0" dev="tmpfs" ino=17874 scontext=u:r:hal_camera_default:s0 tcontext=u:object_r:default_prop:s0 tclass=file permissive=0
2018-11-11 17:32:25.155 709-1426/? E/libc: Access denied finding property "persist.opcamera.supernight"
2018-11-11 17:32:25.155 709-1426/? D/OP_META: [SetBracketModeConfig][404] "SetBracketModeConfig BracketMode:0 fwk_iso:0 fwk_exptime:0.000000 MotionDetected:0 hsDetected:0 isHDRCapture:0 m_CameraId:3 " "fwk_SceneMode:0 isflashsnapshot:0, drc_gain:0.000000, fwk_drcIso:0, eagleEyeDetected:0 GyroFromAP:0.000000 is_motion_detect_enabled:0" "is_static_mode_enabled:0 ROICount:0 m_isNightMode:0 fwk_SceneMode:0 face w:0 SquareMotionDetected:0 GreenRatio:0.000000" "luxIndex:0.000000"
2018-11-11 17:32:25.155 709-1426/? D/OP_META: [AdjustFeature][1493] "AdjustFeature FeatureType:3, isMultiframe:0, isAeBracket:0, m_forceHDR:0, lastFeature:5"
2018-11-11 17:32:25.155 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:25.155 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:1!"
2018-11-11 17:32:25.157 709-1175/? E/CamX: [ERROR][STATS_AEC] ctuningdataadapter.cpp:102: setChromatix m_numSelectors 7 mode 0 submode value 9 usecase 0 feature1 0 feature2 0 scene 0 effect 0
2018-11-11 17:32:25.168 709-1426/? E/libc: Access denied finding property "persist.opcamera.supernight"
2018-11-11 17:32:25.154 709-709/? W/HwBinder:709_2: type=1400 audit(0.0:444618): avc: denied { read } for name="u:object_r:default_prop:s0" dev="tmpfs" ino=17874 scontext=u:r:hal_camera_default:s0 tcontext=u:object_r:default_prop:s0 tclass=file permissive=0
2018-11-11 17:32:25.168 709-1426/? D/OP_META: [SetBracketModeConfig][404] "SetBracketModeConfig BracketMode:0 fwk_iso:0 fwk_exptime:0.000000 MotionDetected:0 hsDetected:0 isHDRCapture:0 m_CameraId:3 " "fwk_SceneMode:0 isflashsnapshot:0, drc_gain:0.000000, fwk_drcIso:0, eagleEyeDetected:0 GyroFromAP:0.000000 is_motion_detect_enabled:0" "is_static_mode_enabled:0 ROICount:0 m_isNightMode:0 fwk_SceneMode:0 face w:0 SquareMotionDetected:0 GreenRatio:0.000000" "luxIndex:0.000000"
2018-11-11 17:32:25.168 709-1426/? D/OP_META: [AdjustFeature][1493] "AdjustFeature FeatureType:3, isMultiframe:0, isAeBracket:0, m_forceHDR:0, lastFeature:5"
2018-11-11 17:32:25.171 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:25.171 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:1!"
2018-11-11 17:32:25.179 709-1426/? E/libc: Access denied finding property "persist.opcamera.supernight"
2018-11-11 17:32:25.179 709-1426/? D/OP_META: [SetBracketModeConfig][404] "SetBracketModeConfig BracketMode:0 fwk_iso:0 fwk_exptime:0.000000 MotionDetected:0 hsDetected:0 isHDRCapture:0 m_CameraId:3 " "fwk_SceneMode:0 isflashsnapshot:0, drc_gain:0.000000, fwk_drcIso:0, eagleEyeDetected:0 GyroFromAP:0.000000 is_motion_detect_enabled:0" "is_static_mode_enabled:0 ROICount:0 m_isNightMode:0 fwk_SceneMode:0 face w:0 SquareMotionDetected:0 GreenRatio:0.000000" "luxIndex:0.000000"
2018-11-11 17:32:25.164 709-709/? W/HwBinder:709_2: type=1400 audit(0.0:444619): avc: denied { read } for name="u:object_r:default_prop:s0" dev="tmpfs" ino=17874 scontext=u:r:hal_camera_default:s0 tcontext=u:object_r:default_prop:s0 tclass=file permissive=0
2018-11-11 17:32:25.179 709-1426/? D/OP_META: [AdjustFeature][1493] "AdjustFeature FeatureType:3, isMultiframe:0, isAeBracket:0, m_forceHDR:0, lastFeature:5"
2018-11-11 17:32:25.183 709-1426/? E/CHIUSECASE: [GetTargetBufferPointer][145] "shared RDI buffer handle:0!"
2018-11-11 17:32:25.192 709-1175/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :1 Red = 1.603189, green = 1.000000, blue = 2.769913
2018-11-11 17:32:25.197 6421-6421/? E/SensorManager: registerListenerImpl sensorName:lsm6ds3c Accelerometer Non-wakeup,isWakeUpSensor:false,callingApp: com.oneplus.camera,callingPid:6421,callingUid:10020
2018-11-11 17:32:25.197 709-1178/? I/mm-camera-CORE: [AFDBG] loadTuningData Cam ID:0 SensorIdx:9 PDType:1 PackageName:1 run_type:1 usecase:0 scene:0 feature2:0 driverIC ID:0x13
2018-11-11 17:32:25.202 709-1179/? I/OPFDManager: Input image dim width 640 height 480 stride 640 scanline 480
2018-11-11 17:32:25.202 709-1179/? I/OPFDManager: Input image dim width 640 height 480 stride 640 scanline 480
2018-11-11 17:32:25.203 709-1179/? E/CamX: [ERROR][STATS_AEC] ctuningdataadapter.cpp:102: setChromatix m_numSelectors 7 mode 0 submode value 1 usecase 0 feature1 0 feature2 0 scene 0 effect 0
2018-11-11 17:32:25.214 709-1179/? E/CamX: [ERROR][STATS_AEC] caeccore.cpp:232: setInput Multi Camera: Peer Info:0xDC1781C0
2018-11-11 17:32:25.216 709-1178/? I/mm-camera-CORE: [AFDBG] loadTuningData Cam ID:2 SensorIdx:0 PDType:3 PackageName:1 run_type:1 usecase:0 scene:0 feature2:0 driverIC ID:0x13
2018-11-11 17:32:25.216 709-1178/? E/CamX: [ERROR][STATS_AF ] af_haf_default_mixer.cpp:587: af_haf_default_mixer_active_algo_selection ACTIVE_ALGORITHM = FOLLOWER
2018-11-11 17:32:25.227 709-1179/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :1 Red = 1.452632, green = 1.000000, blue = 2.303019
2018-11-11 17:32:25.230 709-1179/? E/CamX: [ERROR][STATS_AEC] caeccore.cpp:232: setInput Multi Camera: Peer Info:0xD5FF11C0
2018-11-11 17:32:25.230 709-1179/? E/CamX: [ERROR][STATS_AEC] camxcaecstatsprocessor.cpp:1944 SetAlgoBayerHistValue() Unsupported bayer hist channel!
2018-11-11 17:32:25.233 709-1179/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :2 Red = 1.603189, green = 1.000000, blue = 2.769913
2018-11-11 17:32:25.238 709-1179/? E/CamX: [ERROR][STATS_AEC] caeccore.cpp:232: setInput Multi Camera: Peer Info:0xDC1781C0
2018-11-11 17:32:25.238 709-1179/? E/CamX: [ERROR][STATS_AEC] camxcaecstatsprocessor.cpp:1944 SetAlgoBayerHistValue() Unsupported bayer hist channel!
2018-11-11 17:32:25.238 709-1179/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :2 Red = 1.452632, green = 1.000000, blue = 2.303019
2018-11-11 17:32:25.238 709-1179/? E/CamX: [ERROR][STATS_AEC] caeccore.cpp:232: setInput Multi Camera: Peer Info:0xD5FF11C0
2018-11-11 17:32:25.238 709-1179/? E/CamX: [ERROR][STATS_AEC] camxcaecstatsprocessor.cpp:1944 SetAlgoBayerHistValue() Unsupported bayer hist channel!
2018-11-11 17:32:25.239 709-1179/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :3 Red = 1.603189, green = 1.000000, blue = 2.769913
2018-11-11 17:32:25.239 709-1179/? E/CamX: [ERROR][STATS_AEC] caeccore.cpp:232: setInput Multi Camera: Peer Info:0xDC1781C0
2018-11-11 17:32:25.239 709-1179/? E/CamX: [ERROR][STATS_AEC] camxcaecstatsprocessor.cpp:1944 SetAlgoBayerHistValue() Unsupported bayer hist channel!
2018-11-11 17:32:25.239 709-1179/? D/CamX: [DEBUG][STATS ] camxcawbstatsprocessor.cpp:564 IsValidAlgoOutput() gains from algo for ReqId :3 Red = 1.452632, green = 1.000000, blue = 2.303019