Thank you for the report, I've confirmed receipt of the save and ill get this to the team today. If they're able to offer any insight quickly, I'll be sure to follow up here
I found a workaround for this problem. By salvaging my original home world, the "Civilian orbit slots are being used" red text goes away and I'm able to create a new homeworld. Not ideal since I have to rebuild upgrades of the former homeworld.
I was thinking I couldn't create a new homeworld because the new planet had orbital structures which caused that red text but I think it may have to do with original homeworld civilian orbital structures preventing me from changing homeworlds.