Unfortunetly the Distant Stars version for Rebellion 1.8 still has many bugs when dealing with the solar system planets. I have spend hours trying to make a map of our solar system with GalaxyForge and banging my head as it crashes when I try it. At first I thought I was doing something wrong with Galaxyforge (which I found strange as I had made such maps for Vanilla, Enthrenchment and Diplomacy) but at last I found that the crash was due to bugs in Distant Stars when using certain planets of our solar system.