I'm on OMV 5, I've installed linuxserver/plex's docker with portainer and then I've activated hw transcode by adding device=/dev/dri:/dev/dri command (example) and plex can recognized it (example).
The big issue is that video lags massively but audio works normally.
With hw transoding disable in plex settings sw transcoding works good (video + audio are ok and sync).
May it be a permission /dev/dri settings problem? But if the permission settings were wrong, hw transcoding should not work at all i think.
P.S. I add the same command (device+/dev/dri/:/dev/dri) in handbrake container and it has immediately recognized h264/h265 intel QSV but I have not tried to start encode yet.
P.P.S. Sorry for bad english
Thanks a lot