U2518D, HDR not supported

Hi
I'm trying to activate HDR on Windows settings but it says 'HDR not supported'.
I'm using HDMI 2.0 cable (enabled. HDMI 1.4 is disabled).
Smart HDR is on on the screen settings.
Monitor firmware is up to date.
I ran the DirectX diagnostic tool (dxdiag) and this is the info:
Display Devices
---------------
Card name: Intel UHD Graphics 630
Manufacturer: Intel Corporation
Chip type: Intel(R) UHD Graphics Family
DAC type: Internal
Device Type: Full Device (POST)
Device Key: Enum\PCI\VEN_8086&DEV_3E92&SUBSYS_86941043&REV_00
Device Status: 0180200A [DN_DRIVER_LOADED|DN_STARTED|DN_DISABLEABLE|DN_NT_ENUMERATOR|DN_NT_DRIVER]
Device Problem Code: No Problem
Driver Problem Code: Unknown
Display Memory: 8242 MB
Dedicated Memory: 128 MB
Shared Memory: 8114 MB
Current Mode: 2560 x 1440 (32 bit) (60Hz)
HDR Support: Not Supported
Display Topology: Internal
Display Color Space: DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P709
Color Primaries: Red(0.639648,0.330078), Green(0.299805,0.599609), Blue(0.149414,0.059570), White Point(0.312500,0.329102)
Display Luminance: Min Luminance = 0.500000, Max Luminance = 270.000000, MaxFullFrameLuminance = 270.000000
Monitor Name: Generic PnP Monitor
Monitor Model: DELL U2518D
Monitor Id: DEL413C
Native Mode: 2560 x 1440(p) (59.951Hz)
Output Type: HDMI
Monitor Capabilities: HDR Not Supported
Display Pixel Format: DISPLAYCONFIG_PIXELFORMAT_32BPP
Advanced Color: Not Supported


Why don't I have HDR support? 
How do I enable it?

Thanks
Sam