A Problem I Often Encounter When Colonizing

[thebigsilly]

My colonies will show zero population and so never build anything or contribute anything, while the whole planet is open to my expansion instead of just the little piece that (according to my native habit setting) ought to be available to me.
What's going on? Is this a bug or am I doing something wrong? I have no treaties with other civilizations and my colony ships definitely have the right colony type built on them.