Upon terraforming mars you are left with a planet that has habitat administration and 0 planetary features, so you can only build city and industrial districts.

I actually came here to find a solution to the same issue.

Came very late but a good solution is to just fix it with the console.
Just hit it with a 'planet_size 16' and 'effect reroll_deposits' and that's pretty much it

I haven't played this mod in a bit but just posting this incase another person gets stuck on it.

I know this is very late but I found how to fix it completely with console commands. Using the 'clearflag' command, you can remove the planetary station flag. The command goes as follows: 'clearflag planet planetary_station [target id]'. For example, Mars would be 'clearflag planet planetary_station 5'.

As far as I know this will fix the problem, but there could be another flag on a planet with a planetary station. This could easily be fixed by using the same command by substituting the 'planetary_station' flag with what ever other flag you need to remove. Here is the generic command from the wiki: 'clearflag [type] [flag] [target id]'. If you need to find the flag use the debug tooltip toggle in the console menu.

This only happens if you terraform it AFTER building a station on it, yes?

been 2 years, but I think so yeah

Then just don't build a station on it(or any terraformable planet), if you're planning on turning it into a real colony eventually, simple as.

Apparently there's a real space terraforming mod that might fix this?