I ran into a bug which ruins the game experience if there is no save state before entering The Rot Warren.
The PS4 Pro game is at version 1.04
I only entered The Rot Warren, to activate the level, then I continue onward in the game but avoiding going into the cavern / cave in The Rot Warren level.
At some point when my characters are boosted up, I went back to The Rot Warren via the Zone map.
I receive a dark screen and the characters are falling forever in a loop. You can not move or recover. You can hear the characters talk by splitting up the unit or grouping them again. You can not go into the mutation or Inventory menu. Again you just see the characters falling down a dark hole.
If you do not have a save state before entering the level, you will need to start the game over. At least I found no solution.
I have reproduced the bug twice. It does not seem to matter which characters you have.
The second time I reproduced this problem I had Dux, Selma, Farrow, Bormin and Magnus in my squad.
I hope there is a patch that will address this issue.