Pretty much the title. They walk through the walls and get stuck, sometimes they do not but it stalls my progress nevertheless.
I have encountered the same thing just now:
The game froze at the end as soon as I dug out the minims.
Shortly thereafter the game resumed:
Unfortunately the minims did not resume whatever they were doing.
Edit: From where they are stuck and what happened right before, I suspect minim panicing to maybe have something to do with it?
(Right before wave 1 attacked I did not see any minims stuck in walls, and my economy did not feel as stagnant as it did after the attack.)
Another edit:
It almost looks like my default nest structure (see profile picture) might prevents minims from getting stuck in my other sessions?