Issue with Macbook Pro HDMI to Denon AV receiver?
Is that the MBP with only USB-C ports? How do you connect your MBP to Denon? via some kind of USB-C to HDMI converter?

I've personally tried many different kinds of converters and have been disappointed by them. Pretty sure that's the root of your problem though. Be sure that the adapter you use does NOT support DHCP 2.2