Regarding the Disintegration Doctrine achievement.
I had to load a save about 6-7 times before it worked, I tried the fog of war cheat to check what I was missing but there was nothing missed. I tried different ways of ending the mission with different enemy units still alive.
The one time I actually got the achievement was when I actively hunt down the carriers on the top left and right outside the terrain. You can reach them standing close to the edge and bait them under the terrain to kill them.
Perhaps carriers creating interceptors or something makes the achievement unavailable. Don’t know but worth a try if you can’t get it done. Also killing the last structure right after killing Narud might have been the answer as well, good luck.