I put a motion activated dimming switch (KS220M) in our bathroom, but it keeps turning on even when the room is empty. Every time after I've turned off the light (either via the app or via the switch) it turns back on after the duration of the Manual Off Buffer (no matter the value) has passed.

My Smart Control rule is set to 

* On: Trigger on motion, then set brightness to 100%

* Off: No motion for 10 minutes. (but I've tried other values, all the way down to 15 seconds)

Ambient Light sensor is off.

Things I've tried:

* Different motion sensor sensitivities. 

* Covering the window across from the switch with a towel

* Putting tape over the motion sensor

* Completely covering the switch itself with a piece of paper

No matter what I do: as soon as I turn it off, it turns back on after a few seconds (or whatever Manual Off Buffer is set to). Only thing that prevents it from not turning on automatically, is turning off the Motion Sensor, so that rules out other automation rules triggering it.

This KS220M replaces a non-smart motion-activated dimming switch from Lutron that had 0 issues.

Does anybody have an idea what could be causing this? Other ways to debug the motion detection?