For future reference, Please turn VERBOSE logging OFF. It outputs far more data than we need (it logs every packet) which makes diagnosing much harder.
The errors I’m seeing look like the Transcoder is using Dolby audio and converting to AAC.
Where is the transcoder’s temporary directory ?
I ask because if the transcoder cannot set up notification for the temp directory then the Easy Access Encoder (which converts Dolby audio) will fail.
What type of audio is in the MKV you played in the example logs you provided?