I had that problem, found this threat that points to a board fix that fixed it for me
Has anyone elses mouse randomly been centering on the screen in 7.3.5? • r/wow
TLDR; type /console rawMouseEnable 1
My prediction: Bliz announce a new game that used to be Titan, but is so disappointing for Titan that they had to officially "cancel" Titan so that you wouldn't think it was Titan
Made so many WeakAuras effects to put the remaining duration on a debuff over the button that casts it makes me boggle that this isn't an option in default