Here's two that come to mind.
Having to sometimes click a questgiver 3, 5, 10, 15 times in order to get the dialog to open and stay open. (Been like this for, I dunno, six months? A year?)
Invisible Lei Shen Burial Trove chests. (Hang on to the keys and hope you can see the chests next week. Been like this since late last year.)