this has just started happenng for some reason.go to start GSX..ctrl+shift+F12 only in P3D v5.1..V4.5 is fine
As explained so many times, the menu you see there it's not the "GSX menu". It's the standard Simconnect menu that is shared by all applications (SODE, ActiveSky, etc. all use the same menu), it's created entirely by the simulator, and the application that use it doesn't have any control over its appearance, location or function.
Which means, whenever something is not working on that menu, it will affect all applications that uses it at the same time, and none of them can do anything to fix it.
In P3D 5.1, the menu system was changed from Scaleform to HTML5. A known issue is that you update the sim using only the CLIENT, the menu won't work, you must update the CONTENT too.
If that's not your case, and you are sure you used the Content or the Full installer, it might be related to drivers. I'd say the GTX 980ti, with only 6GB, it's a bit on the weak side for P3D 5, especially if you use lots of add-ons at the same time ( even 8GB might not be enough in that case ).