So I found nothing to explain what to do outside of dropping group but this just happened to me in a Dread Cellar.
I forced a lock on a chest and then found myself unable to use any skills or attack. I could hold right and press left to 'break free' repeatedly, at a cost of stamina, but nothing else would work (even dodge). My keyboard and mouse were working fine when I tabbed out the game or when I used it to open a menu (I have open skills page on my mouse thumb control) but just stuck trying to break free.
Got myself killed on the next boss and still, nothing happened once rezzed. As SOON as I dropped the group, causing me to suffer the timer, I was able to act. Is there anything I could've done to not drop group and continue with the dungeon (similar to the bug where you're light attacking a thousand times a second for no damage animation bug)?