Thanks for the special FW and the information that you are working on a fix for the HDMI AVR sync issues. Please note the NAD M17V2 is a new receiver but it has a bad HDMI implementation like all the high-end brands
I have 2 setups with different problems each:
1.) NAD as Source switcher and Maestro TX between AVR and Projector:
(HTPC / FireTV / VU+ UNO)-->NAD M17V2-->TX-->RX-->Sony VW760
Here I get sometimes sync issues with 4k/60p RGB 8bit (600Mhz) and 4k/25p RGB 12bit (445Mhz) content from my HTPC (Nvidia GTX2070). If this happens then the projector output a green image or nothing. Funny thing is that if it works, then I can watch all the content without any problems
2.) Bypass NAD and use AUDIO OUT only:
(HTPC / FireTV / VU+ UNO)-->TX-->RX-->Sony VW760 (using AUDIO OUT towards NAD M17V2)
With this setup, I have no issues with Video, only
with AUDIO OUT. After a while, DD+ content from FireTV or HTCP will not sync with my NAD. When I reboot the Maestro, then the issue is fixed.
Hopes this clarifies my setup. My preferred solution would be to fix the NAD HDMI issues
. If it helps, I have as well Dr. HDMI 4k, but not connected anywhere.