Microsoft has the min requirements for an AMD card as a rx 5700. Is it possible any generations before are not supported. I noticed this year aswell my rx vega 64 is no longer supported on Forza Motorsport, a game that ran fine at 1440p medium just last year.
If its the case that the vega 64 is not supported but a F****** GTX 1050 ti or GTX 970 is microsoft just hates AMD users.