Debug Message not working

[LordOfMinecraft99]

I have KSP 1.2.2 installed, and I have a problem with the debug menu. When I hit alt-f12 it does not open I do not have a Nvidia card so i don't know what's going on.

[diomedea]

Which is your OS? e.g. Alt is the Modifier key for Windows; but on Linux you need to press RightShift+F12.

nVidia GeForce Experience is (by far) the most common software interfering with the functionality, as it by default uses Alt-F12 for the FPS on/off in Shadowplay, therefore intercepting any such command while remaining in background. Not having a nVidia GFX would not have required installation of GeForce Experience; however please check it really isn't around on your system.

The above doesn't exclude other software could do the same (intercepting Alt-F12). However no other software doing so is currently known. You may have to stop background applications one-by-one and test each time to find when the functionality is restored (in Windows, Task Manager conveniently allows to terminate anything running), be careful however about not shutting system services unless you know what they do.