I've become so disappointed with Vegas performance that I switched over to Resolve with not just grading/cc-ing, but editing as well. From time to time (with each new build, or even new nVidia driver) I'd open Vegas Pro just to check whether at least the preview window is working - still no joy: if I have my GTX 1080 configured to accelerate T/L, the only way to see the picture is to fire up my Samsung and watch it though my Decklink.... How is it even possible that Magix didn't solve this issue by now?!! Just as an interesting (but also confusing) fact: the preview works OK with VP 13...
Piotr