Some of my Lines in Model-viewports in LayOut look different than in SU... why?

Suddenly, some lines are light-gray instead of black:


all black in SU:

Seems like it’s not a style thing, as only the main building has gray lines, the stuff at the top is showing correct.
So i suspect it’s a property of the geometry, material or color that i accidentally added to a group?
But i can’t figure out what it is…
Any ideas?
EDIT:
At around the same time i started to notice something in SU, that i now realize is related, but i don’t see how:

Like I said in the other thread, share the file. Upload the LayOut file so we can see what you’ve got set up.

Done:


This is what I see when I open your LO file…

The content on the VP exist /kept HATCH layer masks some edges when that layer is turned on.

I also notice you’ve modified the scene called P EG 2D New in LO which is not a good thing to do.