I have this also... looking for a fix.

edit: it's certain planets, becoming more and more common as you get further from the galactic core, which makes me think something is up with some of the outer rim background texture files or something like that, but really I have no idea.

It's totally random. Game just fails to load the background texture sometimes because it's a larger file format so as to not look pixelated by the usual texture format. Game just from time to time fails to load it so it's just pure light texture rather than the actual nebula texture.

Thanks for the explanation! Anything I can do on my end about it?

I have had some success, not stopping the bug but resetting it. I do this by closing and reopening the game. I had thought it was a RAM based load issue, and it seems to generally reset the issue for me where it wont happen for several battles.

I know this thread is kinda dead, whatever, but just for EmperorNiko, when I get this bug, it's always the same systems, even across different saves/factions/campaigns, etc. so it's specific files that aren't loading for me. It's a persistent bug, at least for me. Just thought I would pass that along.

Me happened the same but after a restard of the game and a load of the last autosave it worked.