Please forgive the title. I’m not sure how to describe it better 
After starting a project this happens in editor until restart. Completely unworkable situation.
After starting a project this happens
in editor until restart.
Is the resolution scale in the Settings → Engine Scalabiltiy set so something else than 100%?
Checked it firstly. 100% there is 
Is there anything special about your setup? Desktop overlays? Wallpaper engine? Non standard resolution? Custom drivers?
And it only manifests once you’ve PIEd once?
Are the weird plugins also a part of the other, working fine projects? Not saying they’re responsible but who knows… ¯_(ツ)_/¯
Grasping for straws as nothing tangible comes to mind, that’s all.
Is the issue you’re having 100% reproducible?
You could look up the plugins on the marketplace and check out the comments - perhaps it will shed some light or, at least, eliminate them as culprits.
I’ve been hanging around AH for some time now, never seen anything like that.
Hm, I’m not sure. I didn’t make this project at first place. I wish I knew where to look.
PC setup has nothing to do with it. Other 50 projects were always fine. The UE4 intro is used here ans some weird plugins, but they shouldn’t mess with Slate…
Some of them I see for the first time, I admit. “Loading screen” and “GamepadUMGPlugin” sound suspicious for me…
I thought maybe this is a more common issue.