@Wayne-TP 

Thanks for the tip. 

I was having the same problem and just wanted to note a few things about my scenario and what I specifically had to do to get mine working again. 

First, when my vacuume started having issues, it was because it got stuck half on a desk foot that was on the edge of the restricted area. It wasn't able to get itself unstuck and eventually I had to lift it up and set it down outside of the restricted area. This is when it got into the infinite loop of trying to start cleaning, doing one circle, and then says "Restricted area detected". 

To fix it I tried at first to just remove the restricted area from the map that it was cleaning at the time that it first hit the error. That didn't help.
Then I deleted the other map (which was not in use at the time of the error, but which also had a couple of restricted areas). That didn't help

Lastly, I tried to delete the current map entirely, but in order to do that I needed to get it to make a new map so that the current map could be deleted. (I just put it in a small room so it would map quickly). Once there was a new map, I could delete the previous map which had the original restricted area and TA-DA. Problem solved. 

Hopefully this helps the next person that runs into this issue.

  @Leckster 

hey guys, I've figured out what has been causing my RV20 Pro Max to do this.

The charging dock is in my bedroom.

everything works fine until I mark my bedroom as a carpeted area in the app.

note, I have not yet attached the mop pad to the vacuum (ever at this stage).

when I try to start the vacuum, either to clean the bedroom, or other areas, it does a single spin, says restricted area detected, and won't work.

this morning, I tried unmarking the bedroom as a carpeted area, and it is now working perfectly.

I had tried rebuilding the map as others have suggested, and have never added restricted areas to the map myself, but everytime I mark its home area as carpeted (the only carpeted area I have), the issue reoccurs. 

this needs to be addressed in a firmware update, although releasing these doesn't seem to be a priority of TP-Link. Disappointing.

hopefully this can help others in the meantime.