ETA: more detail about the problem
Hello! I don't know if this is a known issue, I couldn't find it anywhere else, so I am asking about it here.
The problem is that when I am at certain vessels, but not all, right-clicking on a part does not cause the part's pop-up dialog box to appear on screen.
Part dialogs still appear on other vessels, and they appears in the VAB. So I am pretty sure it is not a right-click mouse input issue.
There is a weak, partial workaround: I can get some part dialogs to appear by going through the resource tool and selecting a resource, which causes the relevant part dialogs to all pop up for that resource, as expected. I can then pin the dialogs I want and turn off the resource, now free to transfer resources or whatever else I want. But there are some limitations: a) not all the part dialogs appear, sometimes the one I want does not appear; and b) it only works for parts with resources, not (for example) engines, solar panels, etc.
The fact that some dialogs never appear leads me to suspect that the dialog is "mapping" to a screen location that is not visible, i.e. off screen. But that is a very tentative hypothesis, I could be wrong.
Another piece of supporting evidence is that when I use my system's accessibility features to drive the screen pointer using the keyboard only, I can generate right-click events just fine everywhere else, it's just that on these certain "bad" vessels, the right-click does not display any dialog that I can see.
The issue started to appear seemingly spontaneously a few days ago, the only mod I have installed that has been updated in the last few weeks has been Kopernicus, so it doesn't seem like a mod update issue.
Has anyone else had this happen recently?
Edit: I have narrowed the problem down quite a bit though not yet figured it out, it happens any time there are more than about 220 parts loaded in the same local physics bubble at the same time. Even a new vessel does this on the launch pad -- if I go revert and add one part too many, suddenly the right-click menus all stop appearing!
I feel like someone, somewhere must also have had this experience. Anyone??