Since Photoshop CC 2018 update, image now randomly snaps to center when working in a section of it. It's driving me nuts.
Also, a mask will randomly appear and going back in history doesn't fix.
Mac Pro Mid 2010. OS 10.11.6.
Never had a problem with an update before. Also, screen will now randomly flash white.
I had the same problem (very annoying!). I was able to rectify it by uninstalling Photoshop (choose the remove all app preferences option) and reinstalling.
Could probably do it simpler by removing some sort of preferences file somewhere, but the one I found and removed didn't seem to do anything. So this is probably best solution.