Kraken Conquest won’t let me complete

I captured every territory but still says im missing one.

You're going to feel really silly when you find it.

I think its a glitch because It says im not in a position to attack when I go to attack phase.

Probably because you've only got 1 army in the space(s) next to the empty territory.

Look in the darkest background areas. They can make some spots almost invisible.

Turn your contrast up