Specially one area in Act 3, during the "Waiting for Reinforcements" event where you have to defend the oncoming attack of monsters, there is a bug where my grenades fall through the elevator's floor that the monsters are on in the 2nd part of the event.

I tried throwing specifically the Fire Grenades, which were the ones that fell through. I did not test if un-runed or other variations of the grenades would repeat the same thing.

To put it in perspective, I had to kite the monsters onto the keep's roof in order to successfully kill the monsters with only my grenades, as the grenades literally fell through the elevator's floor.

It's obviously a low priority bug, but still something I wanted to pass along.