campaign over with scenarios remaining

[survivor]

Why do campaigns end when there are scenarios remaining. Do I not have enough prestige? Did I do them in the wrong order? Just want to get my money's worth

[Tomislav Uzelac]

You need to win certain scenarios with a "Decisive Victory" or "Brilliant Victory" to unlock further progression.

Which victory is required is displayed in the lower right part of the campaign map, just above the Reload button.

There is also an explanation in the Campaign section of the Manual.