Viewport Resolution Issue "DPI"

After downloading the newest version UE4.18, i noticed right at the beginning that someting is wrong. When starting the editor, the black and white UE4 label with my project name and editor version showed up way to small. After beeing in the editor i noticed that my FPS are jumping between 8 and 30 FPS on a blank scene, wher usually im all the time on the cap of 120 FPS. Also the FPS counter is showing up way smaller than usual.

Im wortking on a Samsung 4K monitor and it seems like the viewport in Ue4 is not longer showing 4K, it looks like everything is scalled up to 8K… I never had this kind of problems in 4.17.2, so i guess it has to be some kind of bug.

Same thing is happening to me, since 4.18, my editor UI is weird and I have to tune Widget Reflector to 0.8 to get it looking normal again, and that sucks since Widget Reflector doesn’t save and you always have to change it when you open the editor.