Converting DNxHR gives error

[baker99]

I get the following errors when hitting convert -

[libx265 @ 00000204994ace80] Invalid value for transfer: bt2020.
[libx265 @ 00000204994ace80] Invalid value for colormatrix: bt2020.
[libx265 @ 00000204994ace80] Unknown option: colorspace.

The medianfo for the file is below, I'm trying to convert to x265 mp4 with ultra UHD settings

General
Complete name : G:\rsUntitled.mov
Format : MPEG-4
Commercial name : DNxHR 444
Format profile : QuickTime
Codec ID : qt 0000.02 (qt )
File size : 189 GiB
Duration : 15 min 28 s
Overall bit rate : 1 747 Mb/s
Encoded date : UTC 2022-07-04 18:06:20
Tagged date : UTC 2022-07-04 18:06:20
Writing application : Blackmagic Design DaVinci Resolve Studio

Video
ID : 1
Format : VC-3
Commercial name : DNxHR 444
Format version : Version 3
Format profile : RI@444
HDR format : SMPTE ST 2086, HDR10 compatible
Codec ID : AVdh
Codec ID/Info : Avid DNxHR
Duration : 15 min 28 s
Bit rate mode : Constant
Bit rate : 1 747 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 (30000/1001) FPS
Color space : RGB
Bit depth : 10 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 7.028
Stream size : 189 GiB (100%)
Encoded date : UTC 2022-07-04 18:06:20
Tagged date : UTC 2022-07-04 18:06:20
Color primaries : BT.2020
Transfer characteristics : PQ
Matrix coefficients : BT.2020 non-constant
Mastering display color primaries : BT.2020
Mastering display luminance : min: 0.0001 cd/m2, max: 1000 cd/m2
Maximum Content Light Level : 1000 cd/m2
Maximum Frame-Average Light Level : 400 cd/m2

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 15 min 28 s
Duration_LastFrame : -17 ms
Bit rate mode : Constant
Bit rate : 192 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 21.2 MiB (0%)
Default : Yes
Alternate group : 1
Encoded date : UTC 2022-07-04 18:06:20
Tagged date : UTC 2022-07-04 18:06:20

Other
ID : 3
Type : Time code
Format : QuickTime TC
Duration : 15 min 28 s
Frame rate : 29.970 (30000/1001) FPS