My main thought is 'Wat'.

I have no idea. I've never seen this, and have no idea what would cause it. If I can replicate the issue, I'll fix it.

Same thing just happened to me: http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=820907425

Though I'm not sure it had the shattered planet graphic before terraforming - I only noticed it recently after terraforming completed.

So far this is the only habitat I have in a pulsar system, and terraforming completed after I finished the Yuht precursor quest and found and surveyed their home system of Yuhtaan, which has shattered planets in it. The Unbidden also invaded and were defeated during the terraforming process. I doubt any of that is actually relevent, mentioning it on the off chance it is though, I can think of nothing else particularly notable though. I don't use any other mods that add/change planet classes.

Also, what is the planet class for habitats, that would be used with the planetclass console command? Can probably use that as a manual fix.

Edit: Well, never mind. I tried changing the planet class to a few normal ones as a test and it still retained the shattered planet graphic, so it would probably do the same if I knew the habitat planet class id and tried to change it to that. Very strange.