Hi, I've not been a VW owner for long so apologies if this is a silly question... the step insert on my drivers side door seems to keep filling with water every time it rains. I open the door to get in and all the water seems to rush from the door itself into the step insert. This doesn't happen on the passenger side at all. I've got a 2020 T6.1 which has the diesel heater fit - which I think is what the vent is for on the step insert itself, so assuming this isn't supposed to happen as it looks like the water is fairly close to entering the vent. Has anyone had this before, is it normal, and what should I do? Thanks!