Have you made sure you updated the database and correctly loaded it to the HP-1? If you did update the DB correctly, did you go into your favorites list and update any channels manually? If not, this might be the problem as the DB does not update your separate favorites list. It only updates the DB itself.
I just went through this system:
Central New York Interoperable Communications Consortium (CNYICC) Network Trunking System, Various, New York - Scanner Frequencies
Which is a P25 Phase 1 system and seen there was only one channel listed as encrypted.
I see no other reasons for you not getting audio other then having the mute button on full time. Maybe your card is not loading things correctly, have you tried to format it and reload everything again?