OK - for some reason I had to capture in 10-bit RGB Uncompressed rather than 10-bit YCbCr... Anyway - first glance suggests that the 75% Rec 2020 bars are in the right place on Da Vinci Resolve's vector scope (i.e. in the 75% RGBYCM squares). I'm not a DaVinci Resolve expert by any means - but with a Rec 2020 timeline, and a capture that is correctly flagged as Rec 2020 in Media Info, then I think this is looking good.
On the luminance ramp below the 4 sets of colour bars you can clearly see truncation to 8-bits from the 10-bit source.
Video ID : 1 Format : RGB Codec ID : r210 Codec ID/Hint : Blackmagic Design Bit rate mode : Constant Bit rate : 6 636 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 25.000 FPS Color space : YUV Scan type : Progressive Bits/(Pixel*Frame) : 32.000 Stream size : 1.76 GiB (100%) Language : English Encoded date : UTC 2021-04-15 10:51:44 Tagged date : UTC 2021-04-15 10:51:44 Color primaries : BT.2020 Transfer characteristics : HLG Matrix coefficients : BT.2020 non-constant