First P51 Campaign Mission Bugged?

[InfiniteStates]

I've just had my third attempt at this mission on simulator. The first attempt I quit because like a fool I accepted the side mission - to help the tank escape, but I have better things to do than spend the next 57 years strafing German tanks with a machine gun. Can you even kill a tank with machine guns? I resorted to using my plane as a missile, but after about 20 minutes of that I got bored as well.

So I restarted the mission, ignored the side mission and killed all the fighters harassing my transports. Then the transports just flew around in circles over the target city. After about an hour of this I got bored again and restarted because there was nothing to defend the planes from.

On my third attempt, after killing all the fighters again, the transport planes didn't even bother flying to the target city. They just flew backwards and forwards on a north-south vector about 20 klicks east of the city.

So what exactly do I have to do to pass this mission? I've done it on realistic, but can't remember doing anything particularly special. Is it bugged or is there something I'm missing? Do I need to take out the ground targets around the city? They aren't yellow targets, so presumably they're not important to the mission...