Oh okay, I think I know what's going on, I'll try to fix it ASAP
I think it's because I made some balancing changes to how much the initially hidden "Physics" contributes to the OP-meter. After the change, the default values that were previously okay were not anymore, which disables the "Generate starting universe" button.
I changed it so the game doesn't take into account anything that is hidden (the fixed version should be live now, no version number change). Hopefully the fix works!