neterw is almost right, if you have more players than home planets then you will get the instant defeat, but you will also get instant defeat if you place a galaxy forge map in the map designer folder.
2 the folder locations for galaxy forge maps prior to 1.16 was the program files galaxy folder, and also needed to modify the galaxy.manifest for entrenchment 1.01
the folder locations for sins 1.16 and entrenchment 1.02 are in a folder NEXT to the mods folder called galaxyforge and the map designers should now br in the mapdesigner folder instread of the galaxy folder next to the mods folders
also galaxy forge 3 uses verion 3 map format and 1.05 uses version 1 format and there are a LOT of differences in the map formats between v3 & v1. To create a map for 1.05 you need to use galaxy forge 1.05 to create maps to work ing sins 1.05.