MarkAtk

I have a similar issue, but not quite the same. I had landed on mun, saved and quit the game. When I loaded the save again the vessel was falling through the ground. I tried loading again and after a few times it stayed on the ground and I could continue.

I encountered the same problem. I cannot launch any vehicle from the VAB directly. My current workaround is to save them, go manually to the launchpad from the main menu and select the saved vehicle. When the bug happens from the VAB, the loading screen image for the launchpad stays visible but there is no loading bar or any loading text displayed. It feels like the loading is complete but the image is not hidden. As ClariNate mentions I can still hear some sounds from moving the mouse over invisible ui elements.

Same problem on my side. I tried renaming a vessel and it renamed some other debris.