If you mean exporting then you have to export using the HEVC codec as MP4 does not support 10 bit and VPX has no ProRes export option. Then you should be able to export to the 10 bit and BT2020 colour space options.
Which version of Video Pro X do you have installed ?
What is the video file format and encoding of the 10 bit video files you are using?
If you are not sure, download and install MediaInfo and analyse one of the 10 bit video clips and post the results, see this tutorial on how to setup MediaInfo and analyse a video clip for all the data required.