I have the same problem since some days.
The .wav sound don't play in PM (4.6.5 WIN, VISTA). In Explorer the .wav and jpg are okay. Sound plays with Quicktime or VLC Player, if selected as default or double click from Explorer, PM Play-Button is enable, no sound after press Play - IPTC Dialog. Speaker is okay.
"enable sound playback"? i can't find this in Preferences - which TAB is this?
ps.: sound is recorded with Nikon D3, Update PM 4.6.6, same problem.
pps: No sound works in PM; i renamed a Music-Wav File to the picture Name in the folder; sound Button is displayed in PM, no Sound after Play.
I installed Sony Vegas Studio and Sound Forge Audio Studio 10 - last time!?
How does the play button work!?
Thanks