Only 2 spaces left!
I have noticed this issue as well (I thought I posted about it, but can’t find it right now).
The issue seems to happen not just with custom maps, but using certain combinations of standard map generation. Seems like the map “sliders” should be able to produce working maps always. Maybe a slight tweak at the close configuration could help. (i.e. don’t allow both near stars with 10 stars per player).