Hiya Murph,
Any chance it could be related to power up sequence and timing? If the receiver is on 1st and on the correct input and is ready to receive signal from the player might that help?

Only reason I thought of this is I will sometimes see an HDCP error message on our Pioneer receiver when everything turns on from cold with the Harmony. It hasn't affected anything (no loss of channels or signal), but I only notice it with a certain start-up sequence.

Cheers,

Dan
On-Wall M5HP LCR, QS8 & EP500 in 7.1