Hi @Emmanuel_perez,
I unfortunately can’t give you a solution for sure as I don’t have a Quicksync hardware to test it, but I’ll try to see what I can do.
Yes and no… There’s nothing wrong with the way you did it, but I don’t know whether (somehow) Plex “expects” this directory to be accessible at the /transcode path rather than /mnt2/transcode as you have. The way you have it, the Plex container sees the Transcode share present on your Rockstor machine at /mnt2/transcode with the /mnt2/transcode path from the Plex container. While this shouldn’t be wrong given you specified the correct path in the Plex UI (/mnt2/transcode), I wonder whether Plex expects it to be with the /transcode path. I would be surprised, but you never know.
In your screenshot, the field label Rock-on directory defines the path with which the rock-on will see the share in question (transcode in your screenshot).
Going back to Plex, I would maybe have a look at @Hooverdan’s post linked below as he was the contributor who brought QuickSync support to Plex; they might thus have a better idea than me on what is needed.
Otherwise, I would maybe make sure the local dir looks as it should…
ls -la /dev/dri
… and that all requirements on the Plex side are met, for instance it seems you may need a Plex Pass to use the feature.
Sorry I can’t help more than that at the moment, but hopefully we’ll get to the bottom of it.