Maybe Denon/Marantz will come up with a firmware to make their new 8K AVRs compatible with the major brands - Samsung, LG, Sony.
But in the meantime I agree with returning the X6700 and using the X6400 until there is a fix.
Yamaha is supposed to test HDMI compatibility with all major brands. Maybe their new 8K AVRs will be compatibility with the 8K Samsung, LG, and Sony.
I definitely don’t think a high-end 8K Samsung TV is junk.