Well, I’m basing myself on your pictures and recreate that part of the diagram after which I try to apply and mess with settings which theoretically could influence things. So, for example, after setting up a diagram I tried to bring model elements to the front and back to see if that influenced things.
I also tried if other (unrelated) elements could be interfering. For example: I couldn’t help notice that both labels under the decision nodes (your first shared picture) were cut off, so I wondered if there might be some (invisible) element(s) which somehow affected both those labels. And I also started experimenting with alignment and layout options.
Just so we’re clear: I’m merely an enthusiastic fellow VP user who simply enjoys trying to help others (also because I hope to learn more about the VP this way). But although I have a solid amount of experience I’ll be the first to admit that there’s plenty of stuff which I don’t know about yet.
Good call! If there’s anyone who can make heads or tails out of this it’s them. And if there’s one thing I learned about VP (the company) over the years it’s that they’re always doing their best to help us out with our problems.
The only idea I have left is to try using a fresh environment. Help tab => ‘Switch workspace’ option. Your workspace is where VP stores its (local) data, this includes diagrams but also (preference) settings. You could try to point that to a new (empty) directory. This would start VP somewhat fresh without any of your preferences and other settings.
Then locate & load this project and see if it reacts in the same way. If it behaves normally then my guess is that some customization options somehow started to interfere (though I can’t really imagine how that would work).
And if it doesn’t change anything then there’s no problem: just switch workspaces again and this time point it to your previous workspace folder, then everything is back to the way it was.