I feel the pathfinding/barricade system's not entirely fleshed out yet.
I use barricades as makeshift walls to cover up accidental “backdoors” to my dungeon. Enemies would still try to get in through them instead of my main entrance. This makes sense, but it seems barricades don't have a health system (yet). So the enemies just end up stuck/hanging out outside the barricades.
I don't have the same low fps as freemanmtc when this happens, since my enemies could still move around (not completely stuck).
A possible solution is to have creatures have a visible “confused” state to inform players that there's some issues in pathfinding. The creature would just stand around the general area until the pathfinding issue is fixed (either removing obstacles, digging a path, or manually controlling the creature).