I've noticed that city-state allies don't seem to be giving me their strategic resources. I check to make sure they were developed and even paid to have the improvement a couple times, but I receive zip. I still receive luxury resources, and all of the other ally bonuses. Is there some new mechanic at the root of this? Or is it some sort of bug? Has anybody else noticed this? Edit: The problem seems to be city states that have pre-existing mines on newly available resources. When this happens they won't gift the strategic resource. You can't pay to "re-improve" the land, and it seems to lock off that strategic resource for the rest of the game. Is this a widespread phenomenon? Has it been noted as a bug?