SkyQ needs to have an EDID that it likes to allow you to select 2160p 10 Bit. If it does not have an EDID it is happy with it will not allow you to select 10 Bit colour and it will not offer the option to download UHD HDR content and will not play previously downloaded HDR UHD content.
The easiest way to to do this is to copy a real EDID from a real TV that supports 4K HDR. You do this for the encoder attached to the SkyQ set top box. Firstly, pick the latest 4K TV on the network and route the video from SkyQ main box to that TV, Then login to the MXNet web GUI and for the encoder attached to the SkyQ box, pull down the EDID menu and scroll down to the option Copy From Output and select the decoder attached to the selected TV. You should see a message saying the copy was successful. You should then be able to go to the SkyQ main box menu and set it to 2160p 10 Bit colour.
At time of writing to access HDR content on SkyQ the subscriber will need to have a Sky Cinema subscription and have the UHD subscription. On the main Sky Menu go to Sky Cinema and go to UHD content and select a movie and scroll right to the option to Select Format and you should see an option for UHD HDR. This is likely to be 15 Gbytes so may take a while to download.
Under the rare circumstance that you are unable to copy a suitable EDID from a real TV, you also have the option of sending your own EDID. To do this pull down the EDID menu for the encoder connected to the SkyQ box and select User EDID,. A dialogue box will pop up allowing you to paste an EDID. Copy and paste the EDID below and press Send. Again you should see a Success message and you should be good to go.
00 FF FF FF FF FF FF 00 4D D9 04 AA 01 01 01 01
01 1D 01 03 80 AA 60 78 0A 0D C9 A0 57 47 98 27
12 48 4C 21 08 00 81 80 A9 C0 71 4F B3 00 01 01
01 01 01 01 01 01 08 E8 00 30 F2 70 5A 80 B0 58
8A 00 A9 BF 63 00 00 1E 02 3A 80 18 71 38 2D 40
58 2C 45 00 A9 BF 63 00 00 1E 00 00 00 FC 00 53
4F 4E 59 20 54 56 20 20 2A 30 30 0A 00 00 00 FD
00 17 79 0E 88 3C 00 0A 20 20 20 20 20 20 01 F9
02 03 64 F0 58 61 60 5D 5E 5F 62 1F 10 14 05 13
04 20 22 3C 3E 12 03 11 02 65 66 3F 40 2F 0D 7F
07 15 07 50 3D 07 BC 57 06 01 67 04 03 83 0F 00
00 6E 03 0C 00 30 00 B8 3C 2F 00 80 01 02 03 04
67 D8 5D C4 01 78 80 03 EB 01 46 D0 00 44 03 68
88 62 76 97 E2 00 CB E3 05 DF 01 E4 0F 03 00 30
E3 06 0D 01 01 1D 00 72 51 D0 1E 20 6E 28 55 00
A9 BF 63 00 00 1E 00 00 00 00 00 00 00 00 00 46