Make sure you're using the latest version of Galaxy Forge. To be safe, re-download it again from the site. Also, open up your map with Notepad and if versionNumber is 0, change it to 1. That will be proof that you're using an old GF to make these. Changing the versionNumber to 1 will make them show up in game properly.
Also be sure to save the map in your Sins install Galaxy folder, not the user path or the map will auto-end as soon as it loads.