Weird source of light after build


I’ve been working on a scene and for some time now a problem occurs after build. Building seems to spawn intense light (seems like a point light) without a source object in the middle of the scene. I have searched extensively for the cause and found nothing. Even deleting everything from the scene did not help at all since the inserted object were still brightly illuminated by this light.

I did however get rid of it at some points. Deleting some levels from the level outliner eliminated the issue for a time. But the error reoccurred after a few builds anyway. After that the old method did not fix anything anymore. So I found out that deleting the build data file fixed it for a few days. And then it started again and deleting the file again does nothing enymore.

Is that an engine bug? Did anybody come across such behavior too?

pictures, please.

also, are you using an orthographic camera?