The latest release of AVIdemux causes a problem due to it stripping chapters from videos. I converted a bunch of videos to HEVC with VidCoder then used AVIdemux to downmix their multi-channel audio to stereo.

Of course it strips out subtitles and chapters (I've not found a way to make it stop doing that). Every video it stripped the chapters from took a long time to load with PotPlayer and seeking wouldn't work. Normally the playback position can be changed and the video keeps playing. But after AVIdemux strips chapters that can't be done, the playback just stops and can't be resumed.

Fortunately I still had the original files so I was able to extract the chapters from them and mux them into the new files with MKVtoolnix and that fixed them. Simply running them through MKVtoolnix did nothing, they had to have the chapters restored.

Would be nice if AVIdemux would get updated to just leave softsubs and chapters in the videos!