bigboywooly,
I've got just opposite to that,in case of 7th Flotilla Type VIIB U-49.It's is originally based in Kiel (1939 - up to early-mid 1940),and each time I go back to Kiel docks after patrolling,I get such situation:
1.I press "Exit the Patrol".
2.And after that I've got either two options "Continue" or "Docks in Kiel".
3.If I press "Docks in Kiel" - I do get main campaign screen with no submarine equipment menu and,originally,"Null" grid in next mission briefing.
If I do as I mentioned yesterday,everything is OK.