Weird graphical sky bug, is there a way to fix?

I worked on a level for several months on a particular map, and now and suddenly, there seems to be a graphic bug that makes the black -the void- where there should be nothing, appear with strange psychedelic colors.

Again, before I had the standard sky sphere and standard daylight light source. Even with the latter deleted the bug seems to preserve. Which makes me believe it has to do something with the engine?! A shader? render issue? I don’t use any fancy settings or post-process settings at all. Is there a way to correct this issue? It’s just occurring on that one map. UE v4.5.

Hi!

Try to setup this skybox and 2 lights again from scratch. Also does that bug appeared when you updated your project to newer version of UE4 or it’s not relevant?

It did not appear when updated to a newer version. not relevant. It occurred suddenly when I was working with that map one day in December. Normally the map has only 1 light source, the standard directional light! In the pictures above though. there is 0 skybox, 0 lights, which makes me believe it has something to do with the engine. Really bizarre bug.

Doing it from scratch fixes it. But I have a large level blueprint that , when copied over, won’t associate all the right objects to blueprint objects.

You mean this blueprint, when spawned get’s another assets spawned in the level? Could you also supply screenshot from running level to see what objects are actually getting spawned in the level and there properties?
Another thing to double check is the count of materials on the skybox and compression settings of the texture