I have the same problem, happens very often but i found a way to start the missions.
In the game's main menu, open 'Online' then open 'Player Match', and wait till it finishes searching (Usually i get 'No Games Found'). Go back and try starting the mission again, and skip the cinematic, Worked for me almost all the time!
Ticket is for a special unique problem. This is happening everywhere. Even to me. There is a fix required for this. The technical team ain't so dumb that they don't know of this extremely common issue. Flight Simulation with warfare is a dying breed. and H.A.W.X/H.A.W.X 2 and to some extent Ace Combat: AH are the reasons its dying.
I bought the game for PC couple of days ago. After the first start, everything works fine and I can play through multiple missions. But once I go back to the main menu and want to continue, the next mission always tosses me back to the main menu during the cinematic.