I think the Float:MinDistance doesn't work quiet well, i tried spawn some boxes around the map and each box have 600.0 unit distance between the other, but it fails and spawns nearby.
Edit : I might give it a try and try to fix the code, but i don't promise anything
Edit #2: seems like the problem was caused because i was using the origin check function to insert valid origins, because the check distance function is after check function.