DIAGNOSIS The self-empty cycle is failing. Usually, it's a clog in the robot's dustbin port, the base's hose, or the base's dustbag isn't seated correctly.
FIX Start with the robot. Remove the dustbin and look into the rectangular hole on the back of the robot. Check for a hair/dust clog around the small metal flap. Clear it. Then, check the base. Open the lid and remove the dustbag. Reach inside the port in the base (where the bag goes) to feel for a clog in the short hose. Re-seat the bag firmly.
IF THAT DIDN'T WORK The base's suction motor might be obstructed. Unplug the base, turn it over, and remove the five screws on the bottom cover. Carefully check the fan impeller for wrapped hair or debris. Be gentle.
HEADS UP If you run the empty cycle without a bag installed, it will suck debris directly into the base's motor, which is a much bigger problem. Always ensure a bag is in place and sealed.