it turns back to normal behavior when the minimap is off, Resources option doesn't matter.
Normal splitscreen works fine actually. It's the cartographic option, that causes weird behavior. When I switch one of the split views to cartographic it shows the same behavior like when the minimap is enabled. Because the minimap is always in cartographic this even makes sense in a certain way.
I guess that this problem and the inability to render certain effects is caused by the same underlying problem.