I think that all through 1.7 beta I've been noticing that if you go to a planet via the colony management screen, fill in some tiles then hit "done" to return to the colony management screen, the available tiles doesn't update.

Example, at the CM screen a planet shows up as 12(7) and you double click on the planet to go to it, toss in 7 buildings then hit done. The CM screen still shows it as 12(7) whereas before 1.7 it would show as 12. If I click the CM tab again it'll refresh the list showing the updated tile count though.

This doesn't hold true though to any terraforming changes to the planet. If your change added an available tile to the mix, the CM screen updates fine.