I tried it now, and I can confirm the problem is not caused by any of our software. It must be a PD3D 4.2 bug similar to the ones that cause issues to the Simconnect menu having keys being sent automatically to it if one of the numeric keys was pressed before opening a menu.
The reason why I can say for sure it's nothing related to GSX, it's because it happens also with the sample TextMenu application from the SDK, with NO GSX installed
To prove it, I attached the compiled executable from the 4.2 SDK for you to test (with GSX uninstalled):
- Start P3D with no GSX installed. The rudder will work.
- Start the Menuitems.exe, and the right rudder will stop to work as soon as the app starts.
- Close the Menuitems.exe, the right rudder will start working again.
So, it seems you found a new bug that, for some reason, any application that reserve a key, will cause the right rudder key (Enter on the numpad, by default) to stop working. We'll report it to LM.