Hi there. I've recently purchased the Proscenic M8 Pro robot vacuum. It does a great job of cleaning the house and I'm really impressed by it, however, it has never once been able to collect the dust when it connects to the charging station. I have repaired the vacuum but it still doesn't collect the dust. It says "start dust collection" then makes a really quiet noise and then stops. When I pick the robot up and feel the flap on the back of the robot where it connects to the docking station the spring feels way to resistant. It comes up and down when I use my finger but no way is the dock expected to use suction to lift the flap and empty it. Does anyone else have this issue????