Some folks mentioned in other posts that for non-nvidia gpus, plex just uses whatever the first gpu is assigned. I’m wondering if it is trying to use the ipmi graphics instead of the Arc card; with the same motherboard I can confirm that TrueNAS sees & has some access to the ipmi graphics.
Though it’ll break remote view in IPMI, what happens if you disable onboard graphics in the BIOS as an attempted workaround?
Link to posts where igpu gets used instead of ARC GPU.
root@truenas[~]# lspci | grep "VGA"
29:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family (rev 41)
2e:00.0 VGA compatible controller: NVIDIA Corporation GA106 [Geforce RTX 3050] (rev a1)