Audio problem with OPPO UPD-203

Over the past few months, I have noticed a growing audio problem with my OPPO-203: when playing a Blu-ray disc, the video displays perfectly, but there isn't any audio.  (I use the dedicated HDMI audio-only output.)  What I had been doing as a consequence was to turn both the OPPO-203 and my Theta Casablanca IV processor/preamp off and then on -- sometimes more than once -- in order to get them to "sync" and, thus, the audio to play.  Now, no matter what I try, there isn't any sound.  However, if I play a CD on the OPPO-203 and use that same dedicated HDMI audio-only output, the OPPO-203 and the Theta preamp sync and out pours the music.

Does anyone know of a fix for this unusual Blu-ray playback problem?  
27caf0f1 dec0 4b77 bbdf ca80e60a63f7jmeyers
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This might be a compatibility issue on the Theta processor when doing certain bluray audio formats.  You could try discs that have different audio formats:

Dolby TrueHD

Dolby Digital (compressed, usually on a DVD)
DTS (compress, usually on a DVD)

Then contact Theta.
Thanks to both of you for your suggestions.  My OPPO-203 firmware is up to date.  Also, I have a Kaleidescape Alto in my AV system.  When I use it instead (as now I have to all the time), the audio is perfect.

All of the listed formats play using the Alto. I have also used other HDMI inputs on the Casablanca IV; same lack-of-audio problem.  This is clearly not a Theta Digital problem.
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