@ich777I am actually having this exact issue, except I am not seeing any processes in watch nvidia-smi. It is using my 10850K iGPU despite not having it setup to use igpu at all. Im not even sure how it accesses it. I see the activity in my igpu though on gpu statistics.
My trex mining docker uses my P2000 fine, as does emby. I am not running them while I am trying to get Plex to work.
I have tried reinstalling the nvidia driver plugin, tried different driver versions, tried different plex versions and repositories. I even tried a fresh version of Plex thinking maybe my Plex config was bad. My VM is not using any gpus, I have tried several system reboots too. This all used to work fine and then one day a few weeks ago it stopped.
At one point, disabling HDR tonemapping in Plex allowed Plex to use the P2000 again but then that stopped at some point too.
My biggest issue is, when using my iGPU my Plex docker crashes often. I then configured the iGPU correctly and it is more stable but still crashes from time to time. I really need this P2000 working as it was stable as a rock.