Sorry for resurrecting this thread, but I found a possible lead on the impenetrable rock bug.

While I would need to do further testing to rule it out completly, it seems I am not affected by the bug if I don't install the undergames expansion.

It would make sense, since I remember I first noticed the bug around the time I bought that expansion.

I found the issue!

It was a saved scenario game that was causing the issue. I deleted it and now it lets me make another map with the same name again.

I checked out the steam\userdata folder where the game stores user made maps.

The map still exists there, but when I manualy delete that the game just places is back when I start WFtO again.

Even reinstalling the game did not seem to fix this.

The game still seems to think the map exists somewhere, even tough its no longer showing up in the list. As I can't make a map with the same name.

I got an update. It might be a coincidence, but it seems the glitch happens when I have a high creature population in my dungeon.

I see, thanks!

My save\map is technically a scenario rather than a pet dungeon level I made as I wanted to make a pet dungeon version of one of my custom maps:https://steamcommunity.com/sharedfiles/filedetails/?id=1576454457

I use god mode to spawn in anything I want.

(by the way, is there an easy way to copy custom maps to make an alternate version?)

gorestone fortress_20181206210130