Found that these guys were managing to pick stuff up outside their maximum area. I had them on fly mode and they were retrieving gravel I was trying to purge.

As you can see, I'm well outside the area, the only reason the gravel cubes are piled up is because I switched em to walk mode.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2797066382

On a side note, I had a machine revolt a few days back as well. As a one off event while I was doing a LOT of grinding with the bots on fly mode, disassembling a failed ship design... they decided they had enough and ground themselves and random chunks of the base starting with my deco blocks.... was a weird one, removed and replaced them all and it seems to be fine after that.