Playing co-op with a friend I encountered, in the Flooded Tombs (?) level, a situation where the pressure tile was permanently pressed in and would not allow a player to activate it.
However I observed what may have possibly caused this, though I have not tested it to confirm.
- I shot the barrels and arrow traps that were next to the pressure plate with a grenade launcher
- The pieces of debris scattered and one or two landed on the pressure plate, pressing it down
- The pieces of debris then despawned/disappeared as normal, however the pressure plate remained in its down position
So based on that I am led to believe that if a piece of debris that would affect a pressure plate despawns while on the plate, it bugs the plate permanently, until the level is restarted.
Great game with excellent execution though!