This issue doesn't have anything to do with GSX, which doesn't require any updates.
The menu bug came up during the beta, and LM fixed it very quickly and, they said to developers it required a Content update, not that we had to update our apps to support changes to Simconnect, because there were none related to the menu, and after the fixed it, all affected apps (GSX, SODE, etc.) started to work again with no changes required on our part.
Could be that you upgrade to P3D 4.2 using just the Client ? If yes, try to update the Content as well. I always update P3D using the full installer, which might explain why I cannot see any issues.