The kobold does not save the rooms. It determines the areas to be vacuumed anew every day.
It is important not to make any significant changes while it is vacuuming.
That means no moving chairs or opening/closing doors in the area it is currently covering. That confuses it, in a way.
Yesterday, I forgot to keep the bathroom door closed. Unfortunately, I noticed too late that it had already been briefly in that room. So I closed the door when it was about to go in that direction again. After the fourth attempt (taking a run-up, stopping, turning off, taking a new run-up...) to enter the bathroom, I gave in. Five minutes later, it came out again and declared its tour complete.
At first, we rearranged or temporarily removed obstacles. The result: significantly longer vacuuming times, frequent recharging, and a confused kobold driving around.