Not much we can do about it unless you post logs. Please also post the edid of your screen - run:
and attach the edid.dat file
My bad. For some reason my Pioneer reciever seems not to like HDR from the pi4 at times.
I connected the pi4 directly to my tv and HDR plays fine
Strange with the reciever as it passes HDR from shield and AppleTV 4k without issues. I did test same inputs/cables and it seems that it passes HDR at times but only works randomly with the pi4 for some unknown reason.
I will try and reset the reciever to factory default and see if that helps. but another day, there is a lot to configure etc after a reset