Noticed the issue in another area this evening.
I was right-clicking on a sprite and the context menu disappeared, and then started creating just a black menu, with no writing to see.
Things I tried;
Resizing the window from full screen to a randomly smaller size. This worked - once, but then when I made it larger again it started failing again.
I also changed the desktop resolution from 1920x1080 to 1600x900, then chose to revert on the Windows prompt. This made no difference. (this had previously fixed an issue where the top of various application windows became a black/white bar).
Now, here’s the third thing I tried, which interesting, DOES work…
As I had my other monitors plugged in I moved the now slightly smaller UE4 window to one of those other screens. Right-clicked - everything worked perfectly. I resized it to full screen and it still worked perfectly.
So - in my specific case, it looks like having Windows using multiple monitors maybe the issue - which was the only change I had made in the last month or so, previously I was only using the one display on the laptop.
What’s a bit odd about this though is that last night I was using the laptop without those other screens plugged in, and I experience the problem. So I dont think its related to having them plugged in, but perhaps related in some way to have a multi-screen setup?
@oatsss, can you confirm whether you have multiple screens also?
Incidentally, moving the window back from the other monitor to the main laptop display instantly recreated the issue again.
sigh