DIAGNOSIS A blockage in the airflow path between the robot's bin and the Clean Base's bag. This is almost always a physical clog.
FIX First, remove and check the disposable bag in the Clean Base for a complete seal and any tears. Then, detach the robot's bin and look into the orange evacuation port on the robot's rear. Use a flashlight to check for a clump of debris obstructing the port.
IF THAT DIDN'T WORK Check the air filter inside the Clean Base chamber (behind where the bag sits). Remove it and tap it clean over a trash can. Reinstall it.
HEADS UP Never run the Clean Base cycle without a bag installed, and never use a non-genuine bag. It will cause suction errors and can damage the motor.