I have also experienced the same 5 second audio cut out problem with CD playback and have come up with a work around (but not a true root cause solution). It would also randomly switch off the AVR in the middle of a CD track.
Over the winter we did some upgrades and put in two dedicated 20 amp circuits and split up the AV components between the 2 separate sources.
Each feed has a Furman PC Pro power conditioner.
The CD playback was fine when played back on the main circuit with both the Oppo 103D and the Panasonic BPD U 9000, through an Integra DRX-R1.
The problem occurred when the second circuit was energized which fed a SVS powered Subwoofer, and a Sony OLED XBR AG9 TV.
Both the OPPO and the Panasonic 9000 have the 5 second cut out problem, with the second circuit on which has the TV connected. This happens with the TV off or on.
I checked for all firm ware updates and had good quality HDMI Cables.
I tried several old and brand new CD's, and switched the output connections. Even upgraded various HDMI cables. But nothing solved the problem.
In researching the culprit it appears the problem is with the EARC HMDIn circuit that is connected to the Sony TV via HDMI..
For now during CD music playback I have simply unplugged the EARC HDMI cable from the back of the AVR and the CD now play the entire recording without the 5 second skip...
I will have to study some of the solutions listed above but for now pulling the EARC HDMI has allowed uninterrupted CD playback
Hopefully the TV design engineers can revisit this EARC HDMI circuit and provide a default solution to prevent this problem.
Thank you all,
Dan