Hi John,
I work with Adrian and we both have been looking into this issue and tested a couple of displays with the NUC10iFNK and in both cases, we were able to activate HDR so we believe that there has to be something specific to your display model CRG9.
I did a quick search on the internet and found several links related to this issue, not in combination with the NUC but when attached to other systems.
See for example https://www.reddit.com/r/ultrawidemasterrace/comments/bmo4kh/crg9_clarification_again/?utm_source=sh... and one possible explanation is that you need Chroma subsampling (YRbCR422) in order to get 10bit (HDR) at 120hz but we don't have the exact same monitor for testing so at this point I can tell you that the NUC10i7FNK supports HDR, that is confirmed and I would recommend that you reach out to Samsung* support for further assistance on this issue.
Regards,
Ronny G
