I don't have any help to offer, but I am experiencing the same problem with my Pioneer FH-P8000BT. Pairs for phone calls with no issue and everything is clear, but the radio does not even "see" the device as being available for A2DP.
I previously paired a few different HTC phones (all running Windows Mobile) with this radio with no issues. I'm hoping it's a simple fix, but I can't find a single thing in the settings that I haven't played with to try and get it to work.
-Telsta HTC Touch HD T8285 (using on AT&T in U.S.A.)