All of the HDMI inputs on our Concert AVR-7/9 and Maestro M9 support HDMI 2.0 and HDCP 2.2
EXCEPT the STB/MHL input. That only supports up to HDMI 1.4.
So, if you are using that input, first thing to do is try a different input. The Blu-ray might be outputting something HDMI 2.0 specific.
You will also want to disable any HDMI CEC control specific functionality on the blu-ray AND the TV. They can inhibit the signal when passing thru a 3rd party device such as our AVRs.
Plug the Blu ray directly to the TV to confirm that the Blu-ray is truly working. If you DON’T get a picture on the TV with the AVR bypassed, try a different signal coming from the Blu-ray. For example, if you have a test disc in the player, try an internet source such as Netflix or Youtube. A lot of Blu-ray players will default to different formats depending upon what source you select. Not all formats may be supported with your tv.
For example, the Blu-ray player may default to HDR(High Dynamic Range) to output 4K content, but the TV may not support that specific spec yet for 4K.
It’s also always good to try different sources, different HDMI cables and different inputs on the TV to narrow down exactly where the issue is.