I contacted the guys at Oppo Digital about this problem. They identified my Sony TV as the culprit. This was their reply:
Sony TVs (newer models) are unique in that they trigger HDMI handshakes even when they are off or in standby mode. Audio is briefly muted when a handshake takes place, and since the TV isn’t fully on, the handshake can never complete successfully, so you will have intermittent attempts (and intermittent dropouts) occur. The solution is to either have the TV turned on, or remove the HDMI cable from the player.
We have had customers report that they had success by changing the TV to a different input before turning off and also reports of success of using a HDMI switcher before the HDMI connection to the television. Unfortunately, these recommendations did not work for everyone and ultimately the TV either had to be on or disconnected via HDMI.
Sony TVs (newer models) are unique in that they trigger HDMI handshakes even when they are off or in standby mode. Audio is briefly muted when a handshake takes place, and since the TV isn’t fully on, the handshake can never complete successfully, so you will have intermittent attempts (and intermittent dropouts) occur. The solution is to either have the TV turned on, or remove the HDMI cable from the player.
We have had customers report that they had success by changing the TV to a different input before turning off and also reports of success of using a HDMI switcher before the HDMI connection to the television. Unfortunately, these recommendations did not work for everyone and ultimately the TV either had to be on or disconnected via HDMI.