Was trying to colonize my 3rd planet the other night and it wouldn't let me land on any planets. I believe I had population on the colony ship. It was in neutral territory, within my ship's range. The planet itself was habitable. When that wouldn't work, tried going to an empty planet within my territory and still- no luck. Think I still have that game saved, so if anyone has any idea on what to check for or try, I'm open to suggestions.
Also, a Dev request as well: When colonizing, any chance we could get a repeat of the planet's tooltip while on the screen asking you to make the choice between the 3 options. Think it would help to make decisions.