U2718Q, Smart HDR grayed out

The U2718Q User's Guide page 7, 39 only mention using Smart HDR via HDMI to HDMI cable.

Since you are using the GeForce RTX 2080 DP 1.4 out port, you need to search in the Nvidia Control Panel for the HDR option. There could be a way to "toggle" it ON in there. Then the U2718Q Menu- Display- Smart HDR might appear. Let us know.

Could you at least tell me how to "toggle" it? I did as the Nvidia guide told,
* setting output color format to YCbCr422
* output color depth to 10bpc
* output dynamic range to limited
but Smart HDR still seem to be grayed out

Although my RTX 2080 has 1.4 DP that is fully supports HDR, I found that U2718Q DP is 1.2
which is not HDR supported and as I've mentioned that I'm connecting via DP-mDP cable that came with the monitor. So the only option left is to use 3rd party HDMI cable or am I misunderstanding something?

To clarify, does this mean you can get HDR over DP, if you enable it in the NVDIA control panel?  I have a RTX 2080 with only one HDMI port.  I'd like to be able to use that for VR.  But, if HDR only works on HDMI, I won't want to have to swap that out with the dell monitor all the time.

No. I stated an unknown that the other user should test and let us know,

"Since you are using the GeForce RTX 2080 DP 1.4 out port, you need to search in the Nvidia Control Panel for the HDR option. There could be a way to "toggle" it ON in there. Then the U2718Q Menu- Display- Smart HDR might appear. Let us know.".

reviving this for others; the mdp is only 1.2; HDR requires 1.4, so you can only use HDMI from this monitor