I noticed in two different games this strange behavior: If an ennemy capture an outpost and you claim it back AND if your outpost had the Hightower upgrade (increased areao of control) then the following turn you have captured the outpost, the area of control is only one squqre around the outpost instead of 3 for an outpost without a hightower upgrade.

I do not have this behavior with normal (non-upgraded) outposts.

Once you reload the game, the outpost retrieve it's normal area of control, but there is a nasty side effect: All the land improvements that were in the area of control are destroyed.

Here is an example: