When the dirt sensor light stays green constantly, a wiring failure or a failed dirt sensor control board could be preventing the dirt sensing system from detecting debris flowing into the vacuum cleaner bag.
Unplug the vacuum cleaner and check the wiring connections between the dirt sensor eyes and the dirt sensor control board. Reconnect any loose wires and repair any broken wires.
If the wiring is okay, you'll likely need to replace the dirt sensor control board because it isn't detecting dirt signals from the sensor eyes.