I'm not certain if this is an update issue or a lack of feedback on a timer of some kind, but there should be something changed so the player doesn't just sit there wondering what's going on.

When I used my explorer for the first time to locate a new sector and then built a storehouse in it to take it over I noticed the borders changed to the blue color showing that I had taken it over, but it took something around 10 to 15 minutes of me sitting there and building new buildings and creating fish plates in the Provision house before I was notified that I'd taken over the new sector and was granted my promotion to level 9.