While exploring a Hive Mind floor in solo play, I encountered a seemingly impassable doorway into a crystal slot room. None of my heroes could move past the doorway into the room, so I continued on exploring elsewhere hoping there would be another route. I did eventually find another doorway leading to the same room from another direction, but it was similarly blocked by seemingly nothing. The AI follow command caused other heroes to path around the entirety of the level when telling another hero to follow me when both were are each respective doorway. Unfortunately, this seems to be a soft-lock, as the door unlocking pylon is likely on the other side of the crystal slot room that I cannot enter.

If I understand correctly, which is that the string in the bottom right of the pause menu is the floor seed, the floor seed that this occurred in is as follows:

Hive MInd_90 HM01_DL_02_01_LEFT -559871870

Given that it's hard to show "Not able to walk past something" in just a screenshot, here's a short video recording: https://www.youtube.com/watch?v=sSclOAYnvEo