Cannot enable HDR

I have 3 DirecTV OTT devices connected to 3 LG TVs. HDR works on two of them as follows:

  - C71KW-200 connected to LG 49” NanoCell 8600 series (2019)

  - C71KW-200 connected to LG 50” NanoCell NANO80 series (2022)

However, HDR does *NOT* work on this combo:

  - C71KW-400 connected to LG 48” OLED C1 series (2021) via DENON AVR-S760H receiver.

I’m very disappointed that I can’t get HDR enabled on the C71KW-400 when connected to the OLED C1, especially since it worked with a 3 year old LG NanoCell 86 series TV.

Observations when attempting to enable HDR feature on C71KW-400 while connected to LG OLED C1 TV:

• Settings --> System --> Display --> HDR  |  Setting was OFF after LG OLED C1 was connected. (The C71KW-400 HDR feature worked previously with both the LG 8600 series and LG NANO80 series TVs.)
  
  
• After turning HDR ON, a message displayed "Get Ready for HDR - Good news:  your TV supports HDR. To turn it on fully, you'll need to restart your device."
  
  
• After restarting the C71KW-400 the HDR feature was turned OFF again.

C71KW-400 firmware versions:

   KERNEL VERSION = 4.9.282-1-16pre-abrelease-q-wnc-32.2-4

   BUILD = QTG1.201103.001.release-q-wnc-32.2-4

   DIRECTV VERSION = 29.2121.21

   BSL VERSION = 2.2.5.0

   BSU VERSION = 3.13

   BFW VERSION = 4.2.5

I would appreciate help to get the C71KW-400 to work in HDR mode with my LG OLED C1 TV.