So I had a custom game set up with:
9 merchants on a course of 350
Evening time, overcast weather
Wolfpack of 3 U-boats
1 friendly corvette/frigate of each type
Air support present
1 hour mission
At mission time 00:13:17, my destroyer scored a gun kill on contact Able (contact Baker was killed by Mountie, contact Charlie was being attacked by Antler). The game ended, showing a cinematic of a U-boat firing on a merchant ship and announced a Catastrophic Defeat with no convoy losses (huh?), U-boat losses critical at 5 U-boats sunk (but only 3 were set up for the scenario)
https://imgur.com/a/Jl2Rh1Y Video here with audio
Dropped this info at Iron Wolf's Steam forum discussion for bugs, also to their bugs channel on their Discord.
Stay sharp out there tin can sailors!