I was dealing with this issue myself where AA refused to work whatsoever with the latest version of Proton, or Proton-GE. It might just be my gpu that is the issue (Quadro M4000M), but I was able to fix it simply by swapping to Proton-9. Anyways, if anyone has this issue as well, just try swapping to Proton-9 like I did and hopefully it will work for you too.