I just had a game that an AI I was at war with (Ythril, if it matters), plopped an outpost down adjacent to my Capital city. There was a crystal mine 2 tiles away over fields.
The outpost automatically flipped to my possession because it was in the ZoC of my city. (I assume)
Yithril took a massive army (probably strong enough to have taken my capital) to go recapture the outpost. This flipped the ZoC to white, over my crystal mine.
Now, ownership and resources don't update until end of turn, so they sent orders to go destroy the crystal mine (I assume), and moved over top, but at this point, they owned the mine. Now, the Outpost reverted to my control.
The army, then moved off the Crystal Mine, back to the outpost, which started the entire cycle over again.
I was able to build up two Disciples before the loop was broken by the outpost finally "sticking" under their control.
I like that outposts that are within a city's ZoC flip automatically. It makes sense. It also makes for stronger defense in the countryside around a city. However, the AI should probably not focus on these things because of the logic loop they create.
Perhaps make these outposts simply not able to switch when within a city's ZoC, or at least value down their appeal to the AI a significant chunk so that there are no crazy loops like that any more?