Had an issue where the NPC's set to cleaning where stuck trying to walk into a wall to get to a void area behind it that cannot be accessed (the void where an elevator is in the building). Since they clean in rows across the entire area designated, they continued trying to get to it and unstuck wouldn't fix them as they just walk right back to the same spot.

The solution is to simply create multiple clean task areas and avoid selecting the void area where they cannot reach. I actually still have the area selected in my world, but since its in the last corner of the room they would need to reach (the corner towards the bottom of the screen), they seem to ignore it now. Before that the void was near the center of the clean task area and interrupted the row they were mopping along.