Bug or feature?

I have been building two outposts, almost at the same time, but I want my capital in the northern one (more food) while the southern one is meant to be production. But in this turn, HK imposes me to choose (one of your outposts can be turned into a city). I tried but there is no way I can get to the next turn (no force turn) or maybe I am missing it (looked through the shortcuts tho).

If it is a feature, it means I have to wait for the capital outpost to be built and turned into a city before starting the second one... else it looks like a bug.