Campaign bug or feature?

Heya!

In the campaign (first mission) I tried to take over the last planet using influence. After a long time I had influence over the entire map, and when hovering over the enemy planet it said terran influence was about 2x or so. However, the rebellion kept at 0%.

Does this mean you absolutely have to 'eradicate' the planet by invasion in the campaign or did I do something wrong.