1) Usually these incidents are spread by many months. Twice in in two days? I hope that this isn't the new MTBF!
2) This time I applied the most simplified fix and paid attention to what I was doing. Or maybe just got lucky that it fixed itself in one step :-)
I connected the blueray directly to one of the LCD's other (not currently connected) HDMI inputs. Confirmed the video & audio output on the LCD. Then switched back in the BP-Denon-LCD on HDMI path. Surprised myself that it worked.
It may or may not be noteworthy that during this one step there were these other conditions: The projector was on but not selected. The Denon was on and set to monitor 1 (the LCD) w/ BP input selected.
I have a theory or maybe its just a guess about the cause... I think the HDMI HDCP (copy protection) handshake is getting mangled (sometimes) as it passes through the Denon and the LCD can't correct itself. Just a theory. Or guess.