This may or may not be related, but when I imported my save from playing my legit copy of Valkyria Chronicles 2 on my PSP-1000 to my TN-Hen'd PSP Go using Prometheus loader, I got a message telling me that my DLC was invalid due to something about [the hardware being newer than the save], from what I understood that ten seconds I read the error message.
However, given what the error message said, it might not be a problem with cfw/hen'ing stuff, as it was strangely specific about how it was the hardware date being "newer" than the save, which it wasn't (my PSP Go is allegedly a launch model with OFW 5.70, despite me buying a month ago, and my save was from recently).
I thought I'd throw it out there in the slight chance it's related to your problem.