I too have a full cockpit using Prosim 737. Like everyone else, I have the problem of the doors getting out of sync with the new PBR version of the aircraft model, and GSX2. That 'waiting for x door to close' sign is a pain.
I have spent literally days trying to get them to talk together. From what I can work out, Prosim's TAB+1,2, 3, 4, 5, 6 is operating (toggling) the all the 737 model's doors but occasionally does not transfer the equivalent of a SHIFT+E, 2, 3 etc to P3D. Sometimes, you have to do a Shift+E on top of a TAB+1, Sometimes this does not work either. Particularly bad if you save a Scenario with any doors open, or relocate to another airport with any doors open. GTX sees one thing, Prosim sees another status.
I think it is something we need to wait for Prosim to fix. I'm sure it is not a GSX issue. Prosim is the only model I have this issue with.
Aussie