Dungeon- Grinning Dungeon
Bug is that you can bypass the locked door (there is an entirely separate corridor that goes around it) and get to the Endless Coil part of the dungeon prior to completing the first part where it asks you to destroy the demonic corruption. I destroyed 1 of the demonic pillars but while looking for the 2nd one I destroyed the entire Endless Coils worth of creatures. Backtracking I found the 2nd pillar and destroyed it. The first sealed door opens and it asks me to kill the Grinning Fiends (2 of them). However, there is nothing alive in the entire dungeon now and the door remains locked.
I just encountered this bug as well. I ran down the 2nd path past the 1st sealed door, unknowingly, and killed all monsters in the Endless Coil before reaching a 2nd sealed door. Backtracking, I destroyed the demonic pillars which opened the 1st sealed door (which was pointless, as I could already go around it anyhow). All monsters were dead, and I could not complete the “Kill Grinning Fiends” objective to unlock 2nd sealed door to progress.
If it helps, I was also trying to complete the “Hubris Smiles Back” side quest simultaneously when I first entered the dungeon. I was able to get the collectibles for the side quest, but I will have to restart the dungeon from scratch in order to try to get a different layout or go into it with the knowledge to not progress further before destroying Demonic Pillars.