Thanks kapu
Seems like you are right
After having a 2 days rest recovering from this (lol) i did it again and indeed there was the convoy again, though much smaller with a bunch of liberty ships
But at least the game tried to compensate, cause it kept spawning those Rawalpindi look-alike amcs and troopships and some big Cinnamon tankers (I know that's not what they're called but i like that nickname lol)
Then it did it again after a port raid just before I wanted to save so eh
Lesson learned
Save after every minute