Same here but only when the BG is disabled, like you said.
When I was going through the settings one at a time, I noticed my BG node was checked to cast shadows(a hangover from an old version, I think), I changed it to unchecked, in line with the default.xml before I uploaded it here, that was the only difference I could see in the actual node settings, although, before I removed the clutter nodes to upload it there was a few shaders inside it's internal network besides the background shader for stars.
I wonder why that scene has an enabled BG but still shows the problem.
I made a new default scene as advised.