There is an issue with modpacks that include both More Wonders and Unique City-States. No city-states spawn at all, neither do ancient ruins or resources, except the few bonus ones around every player's start location. I've tested bare VP+MW, bare VP+UCS, bare VP+MW+UCS, a lot of mods with MW, a lot of mods with UCS and a lot of mods with both and I'm confident that the issue only appears if both MW and UCS are enabled, irregardless of other mods.
If you are going to try and fix this, I can make you a modpack or several to save a bit of your time. If not, can you please point me in the direction of the map generation changes (as I assume that's what causing the problem) in both mods? Thanks in advance.