Cant liberate city states

[pietro]

Augustus captured a city state i was ally with and when i kicked his ass during a war he declared he asked for peace and i even could ask for the city state city in the peace deal however i could only raze it or kep the city there was no option to liberate the city state! Bassicly if i retake a city state through conquest or peace deal i can't return it as a city state. This bassicly means that you can destroy enemy city states and they can't do anything about it.