DIAGNOSIS This is almost always a clog in the vacuum path between the robot's dustbin and the station's bag, or the station's filter is completely blocked.
FIX 1) Remove the robot and empty its onboard dustbin. 2) Take the station's dust bag out and check if it's overstuffed or torn—replace it if needed. 3) This is the key step: look into the round hole in the station where the robot docks. Shine a flashlight in there. You'll likely see a packed wad of dust and debris in the duct. Use a long, thin tool (like a flexible plastic grabber or a straightened coat hanger) to gently pull the clog out from that opening.
IF THAT DIDN'T WORK The small foam filter inside the station itself, behind a panel, might be caked shut. You'll need to unplug the station, find and remove that filter (consult online guides for your model), tap it clean, or order a replacement.
HEADS UP If you run the vacuum over large debris like cat litter or cereal, it can instantly create a severe clog. It's better to do a quick manual pickup of that stuff before letting the robot loose.