Not sure if it's related to the last update.
Here's my issue...
I have a mission I created in November of 2020. I uploaded it and tested it last year, it worked as intended.
Yesterday, I decided I would update the mission to include additional AI aircraft. I copied the mission and gave it a new name, opened it in the Mission Editor and proceeded to edit it. The original mission had 27 aircraft in 3 flights, the new mission has 63 aircraft in 6 different flights.
When I uploaded it, I saved it as the original mission description. When I created an arena to test the mission, it loaded fine. However, when I started the mission no aircraft spawned but It did show the aircraft in the populate mission tab.
Figuring it was just an issue with the rename, I created an entirely new mission using new waypoints. Still no aircraft spawn.
I have attached the mission for closer examination.
The mission is uploaded as Fortress Europe Demyansk 1942, password is TEST