I've noticed in my game that was started weeks before the food build, tiles would randomly show damage when there's no way for a dupe to get to them. I had some tiles in a shallow pond with clean and dirty water mixed and a square of 4 regular tiles were showing over pressure damage when there was no reason for it. I ordered the game to change them to insulated tiles and the damage stopped for a short time. Eventually they started taking damage again. The only thing I could think of, there was a polluted water spillway over two of the tiles. It still didn't really explain it. The temperature of the water was around 80F so it couldn't have been heat. There were gas and water pipes running under the tiles and the pressure in them seemed normal. It was just weird.
There was one other part of my game I noticed this happening and those tiles were also unreachable. My Dupes couldn't even repair the tiles. So eventually the tiles just gave way. There were two of the name normal tiles above them and living quarters below with cots, statues, and paintings. I think there were only hidden gas pipes running under the tiles but they were empty and not connected to anything. Wish I could have gotten a screen shot. Maybe it's because it's an old save?
Steps to Reproduce
Not really sure how to reproduce because it seemed so random. I was wondering if it was a ghost dupe that was stressed and floating around hitting the same tiles. Wish I could give you more information. I played a bit past the problem and if I see it happening again, I'll be sure to get some screen shots and send you a game save.
This issue has not been confirmed by a developer yet.