HDR not working on second display

[themikea 1]

I have dual displays with identical specs and settings, currently they are both set to:

3840x2160 60Hz, 10-bit, RGB Color, HDR enabled (in Windows 10)

When I am in the game settings, I can enable HDR on my main display, but if I change the game to output to the second display instead of the first, HDR is greyed out and cannot be selected.

Both displays are connected to an RTX 2080 Ti with DP1.4 cables and are capable of HDR in other apps/games.  Is there any reason the game will not allow HDR to be enabled on the second display?

[Taggg 3]

Having the same issue with a GTX Titan X. HDR doesn't work on display 3 despite Windows 10 enabling HDR on that display.