Ok - I found a mistake in my blueprint where I was loading the default lighting (possibly) before the engine knew what that default lighting was. I also put all the reflection actors in the persistent level now. This way they never stream and there is no problem with multiple reflections existing in the world (although hidden but it seems to me that all reflections are updated no matter if they are hidden or not). It works fairly good this way but I am still not entirely convinced that the correct reflections are always loaded or updated.