Finally got it working! You're right, it only happens when I alt-tab out of the game!
Thanks for all your help!
With these mods the aircraft seems much more agressive, had to crash dive at the very last second multiple times to save my boat from airborne attacks. There are a lot more fishing boats, never seen one before, first time I got one I didn't know it was one when I spotted it, so I spent around 20 minutes repositioning only to find it was a mere fishing boat
I managed to finish british coastal waters and breaking the fortress by Oct 7, now I haven't got more missions, just patrolling.