Hello @John_Swanson_Swanson,
I have been doing some research on this issue and have found some information on the Intel forums relating to 24/192 HDMI playback on the NUC. On page two of the thread, it seems as though some users have been able to successfully re-enable 24/192 multi channel playback by rolling back the audio driver to an older version. Here’s a link to the thread
https://communities.intel.com/thread/115625
-John