I know that P3D has a problem with the transparent windows. But my feeling is, their might be a problem in the communication between GSX and P3D.
No because, as confirmed multiple times on LM forum, it happens when any transparent window, sometimes even the default ATC with NO GSX installed.
But it doesn't happen immediately, sometimes you must use it many times before you see a crash, and that's why you are probably assuming it's a "communication problem" in GSX: because you are using the GSX menu more often than other apps, so you only increase the chances for a crash to be happening.
As already explained, several times, the Simconnect call to create a menu hasn't changed in YEARS and surely hasn't changed in P3D V5, the call is exactly the same, used in exactly the same way as it always was so, if it really was a GSX problem, you should have happened in all simulators just the same, because the "communication" between GSX and the sim to create a menu is SUPPOSED to be IDENTICAL.
It's again the old story, which already happened a couple of years ago when P3D 4.0x something had a BUG in the menu, which made the entries to be automatically selected without doing anything, and back then people were also absolutely convinced "it was a GSX problem" because, of course, even back then GSX was one of the most popular apps that used that menu, and that bug in the sim made it almost unusable. Of course, the problem was fixed by LM with an update, with no changes required on our part.
And yes, since the crash happens in VCRUNTIME, it's possible it might be related to a problem with VC++ redistributables, in a way that perhaps, a Microsoft update is preventing a crash but, again, it's entirely outside our control.