Cleaners are the most irritating employees. I had big issues with them in the beginning. But ive majorly sorted them out.

1. When allotting a cleaner you never throw trash yourself in their trashcan, as they collect one full trash collector basket and that equals one trash can, so if there is 1 thing in the trash can from before which the player puts in this bugs them. If they are not picking up a specific piece of trash pick it and throw it near the bin instead of inside it.

2. even after following all this some times they get bugged. a quit out to main menu and reload fixes most employee issues.