[ONE Original Android Development] SethGeckoXDA:
Ok, that actually hit me as well today (Mic not working in a Signal call). It worked properly after rebooting the device. So, it seems the issue happens only sporadically. If somebody knows how to reliably reproduce the issue, shoot!

Might be related to this issue.

Log:

07-09 14:11:32.970 12400 12400 I TelecomFramework: UserCallIntentProcessor: sendIntentToDestination: trampoline to Telecom.: UCA.oC@AAA
07-09 14:11:33.095 12400 12400 I TelecomFramework: UserCallActivity: onCreate done
07-09 14:11:33.206 715 715 I chatty : uid=1000 system_server expire 59 lines
07-09 14:11:33.206 715 2860 I chatty : uid=1000(system) uteStateMachine expire 45 lines
07-09 14:11:33.207 715 2864 I chatty : uid=1000(system) CallAudioModeSt expire 9 lines
--------- beginning of crash
07-09 14:11:33.300 377 2197 F libc : Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0xe0 in tid 2197 (Binder:377_3), pid 377 (audioserver)
07-09 14:11:33.366 12435 12435 F DEBUG : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
07-09 14:11:33.367 12435 12435 F DEBUG : LineageOS Version: '18.1-20210708-NIGHTLY-bacon'
07-09 14:11:33.367 12435 12435 F DEBUG : Build fingerprint: 'oneplus/bacon/A0001:5.0.2/LRX22G/YNG1TAS0YL:user/release-keys'
07-09 14:11:33.367 12435 12435 F DEBUG : Revision: '0'
07-09 14:11:33.367 12435 12435 F DEBUG : ABI: 'arm'
07-09 14:11:33.370 12435 12435 F DEBUG : Timestamp: 2021-07-09 14:11:33+0200
07-09 14:11:33.371 12435 12435 F DEBUG : pid: 377, tid: 2197, name: Binder:377_3 >>> /system/bin/audioserver <<<
07-09 14:11:33.371 12435 12435 F DEBUG : uid: 1041
07-09 14:11:33.371 12435 12435 F DEBUG : signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0xe0
07-09 14:11:33.371 12435 12435 F DEBUG : Cause: null pointer dereference
07-09 14:11:33.371 12435 12435 F DEBUG : r0 00000000 r1 008c0055 r2 00000000 r3 00000000
07-09 14:11:33.371 12435 12435 F DEBUG : r4 ad0c0564 r5 00000001 r6 abe79d30 r7 abe79cd0
07-09 14:11:33.371 12435 12435 F DEBUG : r8 af4d9124 r9 af4d9124 r10 af24a448 r11 b0300490
07-09 14:11:33.371 12435 12435 F DEBUG : ip af24bbcc sp abe79950 lr af2263e7 pc af2244ac
07-09 14:11:33.422 12435 12435 F DEBUG : backtrace:
07-09 14:11:33.422 12435 12435 F DEBUG : #00 pc 0001a4ac /system/lib/libaudiopolicyenginedefault.so (android::audio_policy::Engine::getDevicesForStrategyInt(android::audio_policy::legacy_strategy, android::DeviceVector, android::DeviceVector, android::SwAudioOutputCollection const&) const+988) (BuildId: c5f2ef6861302a88743da59d367a6053)
07-09 14:11:33.422 12435 12435 F DEBUG : #01 pc 0001caa7 /system/lib/libaudiopolicyenginedefault.so (android::audio_policy::Engine::getDevicesForProductStrategy(android::product_strategy_t) const+438) (BuildId: c5f2ef6861302a88743da59d367a6053)
07-09 14:11:33.422 12435 12435 F DEBUG : #02 pc 0001cd1b /system/lib/libaudiopolicyenginedefault.so (android::audio_policy::Engine::getOutputDevicesForAttributes(audio_attributes_t const&, android::sp<android::DeviceDescriptor> const&, bool) const+226) (BuildId: c5f2ef6861302a88743da59d367a6053)
07-09 14:11:33.423 12435 12435 F DEBUG : #03 pc 0000bd3d /system/lib/libaudiopolicymanager.so (android::AudioPolicyManagerCustom::checkOutputForAttributes(audio_attributes_t const&)+124) (BuildId: 05f2083db6bf114b31d36564d32778f9)
07-09 14:11:33.423 12435 12435 F DEBUG : #04 pc 0003a467 /system/lib/libaudiopolicymanagerdefault.so (android::AudioPolicyManager::checkOutputForAllStrategies()+106) (BuildId: b0140817566edd506b711b6a0890171f)
07-09 14:11:33.423 12435 12435 F DEBUG : #05 pc 000254f9 /system/lib/libaudiopolicymanagerdefault.so (android::AudioPolicyManager::checkForDeviceAndOutputChanges(std::__1::function<bool ()>)+32) (BuildId: b0140817566edd506b711b6a0890171f)
07-09 14:11:33.423 12435 12435 F DEBUG : #06 pc 0000c42b /system/lib/libaudiopolicymanager.so (android::AudioPolicyManagerCustom::setPhoneState(audio_mode_t)+146) (BuildId: 05f2083db6bf114b31d36564d32778f9)
07-09 14:11:33.423 12435 12435 F DEBUG : #07 pc 000104eb /system/lib/libaudiopolicyservice.so (android::AudioPolicyService::setPhoneState(audio_mode_t, unsigned int)+80) (BuildId: 89396bf069d4e8387bc5f6930d86e70e)
07-09 14:11:33.423 12435 12435 F DEBUG : #08 pc 00054c75 /system/lib/libaudioclient.so (android::BnAudioPolicyService::onTransact(unsigned int, android::Parcel const&, android::Parcel*, unsigned int)+5768) (BuildId: b7e6b5c02d0fcfd799ee2a6f4d39c929)
07-09 14:11:33.423 12435 12435 F DEBUG : #09 pc 0003451d /system/lib/libbinder.so (android::BBinder::transact(unsigned int, android::Parcel const&, android::Parcel*, unsigned int)+144) (BuildId: 486e8e257fc611836c4c865eb1db580b)
07-09 14:11:33.423 12435 12435 F DEBUG : #10 pc 0003a38f /system/lib/libbinder.so (android::IPCThreadState::executeCommand(int)+626) (BuildId: 486e8e257fc611836c4c865eb1db580b)
07-09 14:11:33.423 12435 12435 F DEBUG : #11 pc 0003a05f /system/lib/libbinder.so (android::IPCThreadState::getAndExecuteCommand()+98) (BuildId: 486e8e257fc611836c4c865eb1db580b)
07-09 14:11:33.423 12435 12435 F DEBUG : #12 pc 0003a6eb /system/lib/libbinder.so (android::IPCThreadState::joinThreadPool(bool)+38) (BuildId: 486e8e257fc611836c4c865eb1db580b)
07-09 14:11:33.423 12435 12435 F DEBUG : #13 pc 000542ad /system/lib/libbinder.so (android::PoolThread::threadLoop()+12) (BuildId: 486e8e257fc611836c4c865eb1db580b)
07-09 14:11:33.423 12435 12435 F DEBUG : #14 pc 0000ed43 /system/lib/libutils.so (android::Thread::_threadLoop(void*)+170) (BuildId: b8dfed2088aad5ea02c25267aaef3e88)
07-09 14:11:33.423 12435 12435 F DEBUG : #15 pc 0000e881 /system/lib/libutils.so (thread_data_t::trampoline(thread_data_t const*)+264) (BuildId: b8dfed2088aad5ea02c25267aaef3e88)
07-09 14:11:33.423 12435 12435 F DEBUG : #16 pc 0008221b /apex/com.android.runtime/lib/bionic/libc.so (__pthread_start(void*)+40) (BuildId: dfd35824296878c5e25149d780dd7d13)
07-09 14:11:33.424 12435 12435 F DEBUG : #17 pc 0003a3fd /apex/com.android.runtime/lib/bionic/libc.so (__start_thread+30) (BuildId: dfd35824296878c5e25149d780dd7d13)