Why aren't my cities' rank rising. Like my smallest one is stuck at 2 and won't go up. The bubble is gray.

Are you playing as the Infernal civ with the fallow trait? (population is not affected by food, you must add manes to a city.)
Are you playing as the Kuriotate civ with the sprawling trait? (Settlements recieve a food penalty and will not grow very big, but your main cities should compensate.)
Do you have "avoid growth" selected on the city governor screen? (deselect it if so)

do you have extra food?

is your city producing more than twice it's population in food?

erm, rank in what?