First install the latest version of the driver for the 1070 card from dell.com (use the service tag).
Then, if no luck, ask Dell customer service.
Did you allow Windows Update to update drivers? That's the default, but a very bad one. If it's fixed, tell Windows to never update drivers.
I have the above mentioned laptop, with a 4k screen, 60Hz and before, it had the option under the display setting to enable HDR on the laptop monitor. I have noticed that now that option has been completely removed and assume this is some sort of software error. I am currently running the 1709 build of 10 and have an nvidia 1070 card on this system.
Would any of you have an idea of where to start to get the system to recognize the monitor as capable so I can reenable this feature?