So I too have/had these DX 12 screen flickers and freezes but something is not right. I just built a new PC and I installed WOW on it, played a few days and everything was great. No flickers,black screens and freezes on this PC. Just now I copied my Interface and WTF folders over so I can enjoy my setup as it was (I did delete the config.wtf file from the old WTF folder since im on a new machine). After the copy the all the problems came back, screen freeze, black screen and everything just like before when I open the collections tab, when I switch tabs on pc, in Dornagal etc.
So I wonder can these problems truely be because of an addon of multiple addons? Before the copy for those few days I had a barebone WoW, only had Details and DBM installed and nothing else.