Dirty sensors

Hi friends. I have the litter robot 4 and I keep getting the dirty sensor notification which in turn causes it to inaccurately say my waste basket is full when it’s not. I get this error about every week. I’ve cleaned the sensors with a cloth, a q tip, compressed air, everything. It’s so annoying. I seriously think something is wrong with my sensors. I’ve done the sensor calibration with the white paper and still no luck. Did I get a faulty unit? It’s not even a year old!