Top Side Crew all dead!

[BULL]

Hmm... I into my second patrol with U-37 and IX type Uboat on the Western approaches to Gibralter. A convoy is coming out of the straight so I fire off a contact report and position for attack. Next thing I know.. out of the mist comes a big old Queen Elizabeth class BB on the port flank of the convoy. I am in perfect position for an attack.... I fire 4 and get 3 hits.. one dud. The BB takes on a heavy list to port. I set up an fire 4 more.... no hits.... maybe I am too close for them to arm because there is now way for me to miss this close. I fire 2 more... one hit. I am out of torpedoes and the wagon just won't sink... no way to duke it out with the 10.5cm so I give up. Shame you don't get credit for damaging a big capital ship like that.

So here is the interesting part... I creap away from the swarming DDs and surface... its night time and I cruising to recharge batteries.... Some of my crew had been injured with depth charges but all mild injuries... 96/100 type. I leave the game for a while cruising on the surface at 1x speed. No ships in sight out in the Atlantic....I save the game till another session.
Next day I load the file and all my topside crew (including those not on duty) are dead. No damage to the boat but everyone is dead.... Is this a bug? I have never had that happen before.

Anyone ever see this?