Having the same issue with Dragon Age II, I captured a video of it. I can play with no glitching if I use DX11 but then I can’t use geometry mode, with DX9 I get this flickering. I tried adjusting every VorpX option with no change. Sorry for my loud birds, I didn’t turn off my mic before recording.
https://youtu.be/sTxNg_VGCWc