[LeEco Le Pro3 Guides, News, & Discussion] morphicts:
Any change for full log? i.e. reboot phone, open IR app, press button -> capture full logcat output, e.g. w/ syslog app.

Or even better, get only necessary stuff via adb:

$ adb logcat | grep -i uei

When IR works, log looks like this:

PHONE BOOTING
03-19 20:34:34.252 1816 1816 W PackageManager: Unknown permission android.permission.ACCESS_IRDA in package com.uei.quicksetsdk.letv
03-19 20:34:36.154 1816 2916 W PackageManager: Unknown permission android.permission.ACCESS_IRDA in package com.uei.quicksetsdk.letv
12-22 22:06:38.212 1816 3705 I BackupManagerService: Next restore package: RestoreDescription{com.uei.quicksetsdk.letv : STREAM}
12-22 22:06:40.997 1816 7472 D RestoreEngine: Need to launch agent for com.uei.quicksetsdk.letv
12-22 22:06:40.999 1816 7472 I ActivityManager: Force stopping com.uei.quicksetsdk.letv appid=10074 user=0: clear data
12-22 22:06:41.235 1816 7472 I ActivityManager: Start proc 7528:com.uei.quicksetsdk.letv/u0a74 for backup android/FullBackupAgent
12-22 22:06:41.235 1816 7472 D BackupManagerService: awaiting agent for ApplicationInfo{b751c6c com.uei.quicksetsdk.letv}
12-22 22:06:41.280 1816 1868 D BackupManagerService: agentConnected pkg=com.uei.quicksetsdk.letv agent=android.os.BinderProxy@70e3235
12-22 22:06:41.307 1816 4509 D VoldConnector: SND -> {35 volume mkdirs /storage/emulated/0/Android/data/com.uei.quicksetsdk.letv/files/}
12-22 22:06:43.260 1816 3705 D BackupManagerService: Restore complete, killing host process of com.uei.quicksetsdk.letv
12-22 22:06:43.274 1816 3882 I ActivityManager: Process com.uei.quicksetsdk.letv (pid 7528) has died
12-22 22:08:19.028 8719 8719 D TS-IRMagic: Trying to bind QuickSet service (for controlling IR Blaster): com.uei.quicksetsdk.letv - com.uei.control.Service
12-22 22:08:19.039 1816 3886 I ActivityManager: Start proc 8740:com.uei.quicksetsdk.letv/u0a74 for service com.uei.quicksetsdk.letv/com.uei.control.Service
12-22 22:08:19.068 8740 8740 W System : ClassLoader referenced unknown path: /system/app/UEIQuicksetSDKLeTV/lib/arm64

STARTED IR APP HERE
12-22 22:08:19.070 8740 8740 D UEI.SmartControl.LeTV: Quickset Services start...
12-22 22:08:19.070 8740 8740 I UEI.SmartControl.LeTV: Manufacture = LeMobile
12-22 22:08:19.073 8740 8740 D UEI.SmartControl.LeTV: Extracting JNI libs...
12-22 22:08:19.073 8740 8740 D UEI.SmartControl.LeTV: --- java.library.path =/vendor/lib64:/system/lib64
12-22 22:08:19.079 8740 8740 D UEI.SmartControl.LeTV: --- Build.SUPPORTED_ABIS:->arm64-v8a<-
12-22 22:08:19.079 8740 8740 D UEI.SmartControl.LeTV: --- Checking lib: libqs_arm64-v8a.zip
12-22 22:08:19.079 8740 8740 D UEI.SmartControl.LeTV: --- Extracting JNI libs: libqs_arm64-v8a.zip
12-22 22:08:19.099 8740 8740 I UEI.SmartControl.LeTV: --- Selecting new region: 8
12-22 22:08:19.101 8740 8740 D UEI.SmartControl.LeTV: QS Service created
12-22 22:08:19.102 8740 8740 I UEI.SmartControl.LeTV: Service initServices...
12-22 22:08:19.103 8740 8740 D UEI.SmartControl.LeTV: QS start get config
12-22 22:08:19.107 8740 8740 D UEI.SmartControl.LeTV: Loading JNI Libs...
12-22 22:08:19.421 8740 8740 I UEI.SmartControl.LeTV: Supports setup maps: true
12-22 22:08:19.422 8740 8740 D UEI.SmartControl.LeTV: QS start statue = true Error code = 0
12-22 22:08:19.422 8740 8740 I UEI.SmartControl.LeTV: QS version = v2.7.7.1_RC1
12-22 22:08:19.422 8740 8740 I UEI.SmartControl.LeTV: DB version = APAC_LeTV_Mobile_2015_i-Three_database_v3.0_letv
12-22 22:08:19.423 8740 8740 I UEI.SmartControl.LeTV: ### init IR Blaster...
12-22 22:08:19.426 8740 8740 E UEI.SmartControl.LeTV: UEIBLaster setting for 616
12-22 22:08:19.426 8740 8740 I UEI.SmartControl.LeTV: Setting serial record hearder size = 2
12-22 22:08:19.426 8740 8740 I UEI.SmartControl.LeTV: Get version...
12-22 22:08:19.437 8740 8740 D UEI.SmartControl.LeTV: waitForReply check queue size: 0
12-22 22:08:19.442 8740 8757 D UEI.SmartControl.LeTV: serial port data available: 21 - 1
12-22 22:08:19.468 8740 8740 D UEI.SmartControl.LeTV: version : 00 13 00 32 35 36 37 30 32 32 35 36 37 30 34 33 30 30 30 30 32
12-22 22:08:19.468 8740 8740 D UEI.SmartControl.LeTV: IR Blaster version: 256702256704300002
12-22 22:08:19.468 8740 8740 I UEI.SmartControl.LeTV: QS saving settings...
12-22 22:08:19.479 8740 8740 D UEI.SmartControl.LeTV: waitForReply check queue size: 0
12-22 22:08:19.486 8740 8757 D UEI.SmartControl.LeTV: serial port data available: 7 - 1
12-22 22:08:19.514 8740 8761 I UEI.SmartControl.LeTV: Device manager: loading config....
12-22 22:08:19.515 8740 8761 D UEI.SmartControl.LeTV: ----------- loading internal config...
12-22 22:08:19.515 8740 8740 E UEI.SmartControl.LeTV: Services init done
12-22 22:08:19.517 8740 8761 D UEI.SmartControl.LeTV: ----------- reading device:LeTV
12-22 22:08:19.517 8740 8761 I UEI.SmartControl.LeTV: ----------- adding device: LeTV
12-22 22:08:19.517 8740 8761 D UEI.SmartControl.LeTV: loadConfiguration
12-22 22:08:19.517 8740 8761 D UEI.SmartControl.LeTV: loadConfiguration.....
12-22 22:08:19.517 8740 8740 D UEI.SmartControl.LeTV: QS Service init finished
12-22 22:08:19.520 8740 8740 D UEI.SmartControl.LeTV: QS Service version name: 1.0.008
12-22 22:08:19.520 8740 8740 D UEI.SmartControl.LeTV: QS Service version code: 8
12-22 22:08:19.520 8740 8740 D UEI.SmartControl.LeTV: QS SDK AIRCON version: v1
12-22 22:08:19.526 8740 8740 D UEI.SmartControl.LeTV: Service requested: Control
12-22 22:08:19.528 8740 8740 D UEI.SmartControl.LeTV: Internal service binding...
12-22 22:08:19.554 8740 8760 I UEI.SmartControl.LeTV: Notify AllClients services are ready...
12-22 22:08:24.742 8740 8758 I UEI.SmartControl.LeTV: Serial port is closed.
12-22 22:08:34.516 8740 8762 D UEI.SmartControl.LeTV: Internal timer expired: 1
12-22 22:08:51.287 8719 8719 D TS-IRMagic: Trying to bind QuickSet service (for controlling IR Blaster): com.uei.quicksetsdk.letv - com.uei.control.Service
12-22 22:09:00.770 8719 8719 D TS-IRMagic: Trying to bind QuickSet service (for controlling IR Blaster): com.uei.quicksetsdk.letv - com.uei.control.Service
12-22 22:09:08.684 8719 8719 D TS-IRMagic: Trying to bind QuickSet service (for controlling IR Blaster): com.uei.quicksetsdk.letv - com.uei.control.Service
12-22 22:09:10.797 8719 8719 D TS-IRMagic: Trying to bind QuickSet service (for controlling IR Blaster): com.uei.quicksetsdk.letv - com.uei.control.Service

PRESSED SOME BUTTONS HERE
12-22 22:09:17.831 8740 8752 I UEI.SmartControl.LeTV: ------ IControl API: 18
12-22 22:09:17.832 8740 8752 D UEI.SmartControl.LeTV: Converting patterns to learned data...
12-22 22:09:17.832 8740 8752 D UEI.SmartControl.LeTV: sendIrPattern...
12-22 22:09:17.843 8740 8752 D UEI.SmartControl.LeTV: waitForReply check queue size: 0
12-22 22:09:17.970 8740 9067 D UEI.SmartControl.LeTV: serial port data available: 3 - 1
12-22 22:09:17.997 8740 8752 D UEI.SmartControl.LeTV: sendIrPattern done
12-22 22:09:17.997 8740 8752 D UEI.SmartControl.LeTV: --- sendIRPattern result = 0
12-22 22:09:17.998 8740 8752 I UEI.SmartControl.LeTV: Control.sendIRPattern: 0
12-22 22:09:17.998 8740 8752 I UEI.SmartControl.LeTV: ------ IControl API: sendIRPattern done
12-22 22:09:17.999 8740 8753 I UEI.SmartControl.LeTV: ------ IControl API: 13
12-22 22:09:19.840 8740 8752 I UEI.SmartControl.LeTV: ------ IControl API: 18
12-22 22:09:19.840 8740 8752 D UEI.SmartControl.LeTV: Converting patterns to learned data...
12-22 22:09:19.840 8740 8752 D UEI.SmartControl.LeTV: sendIrPattern...
12-22 22:09:19.851 8740 8752 D UEI.SmartControl.LeTV: waitForReply check queue size: 0
12-22 22:09:19.975 8740 9067 D UEI.SmartControl.LeTV: serial port data available: 3 - 1
12-22 22:09:20.000 8740 8752 D UEI.SmartControl.LeTV: sendIrPattern done
12-22 22:09:20.000 8740 8752 D UEI.SmartControl.LeTV: --- sendIRPattern result = 0
12-22 22:09:20.000 8740 8752 I UEI.SmartControl.LeTV: Control.sendIRPattern: 0
12-22 22:09:20.000 8740 8752 I UEI.SmartControl.LeTV: ------ IControl API: sendIRPattern done
12-22 22:09:20.001 8740 8753 I UEI.SmartControl.LeTV: ------ IControl API: 13

NOTE: Do not install xposed or any other hack. It works straight out of clean install.