Can't capture city with aerodrome commander

[MutilationWave]

So I'm attempting to capture my enemy's capital city. I have all quarters occupied and the city center. But I can't capture it. There is an icon for the enemy aerodrome commander, but I can't interact with it. I have a unit stationed there, it can't be pillaged.

The only way I can interact with it at all is by sending biplane intercept missions at it. They all fire on it, but there is no damage done and no experience gained. I've tried it from my aerodrome and from a squadron commander airfield. I can't think of anything else stopping me from capturing the city.

At this point I think it's a bug. Has anyone else encountered this? Is there a solution?

 

[MutilationWave]

Update: I've captured all the districts in the city beside the enemy capital now and this one won't capture either. Very strange.