This looks like the transcode bug many people are experiencing.
If you turn off hardware accelerated transcoding does the problem go away?
What version of PMS are you running?
What platform - CPU and OS?
See post below for workaround. Thread is for Synology NAS. Same workaround (delete driver) will apply to other platforms.
You can also fall back to earlier PMS releases. Not sure how far back you’ll have to go. Maybe 1.18.0 or earlier based on other posts I’ve seen. If you happen to be on a Synology NAS, the Package Center has v1.16.5, which does not experience the problem.
