Re: Partial truth, partial cover up ?
German counter intelligence was awful because of common Nazi pathologies: overconfidence in their superiority, paranoia and distrust of rival sister organizations, and reluctance to deliver bad news to higher ups. Lots of Nazis and German generals kept informal channels open to the allies through neutral countries. They weren't spies, just serving their own interests, especially when it was clear how things were going to end.
Plus, the allies were very careful to protect Ultra sources. Quite often they arranged for a plausible alternate event explain their apparent luck. Not many operational commanders were privy to the details. Notably, Patton was a big fan of Ultra and couldn't get enough.