If you have started the war with Amagal, and interacted with the capital atleast once, and they still haven't shown up. You might be missing a step, or ur game is glitched. Have you also done the battle in pavil?
You need to be at least this far for them to spawn. If you are not seeing them, you might be in the post-war phase; you need to be in the war phase, not post-war. If they are still not showing up, and you are in the war phase, you might have ran into a glitch. P.S. If you have started the war with Amagal and they are not showing up, try waiting 1 turn. You can do that by having your soldiers advance until you spend all your AP for that round.
