All drivers you need for your NUC you can download here: Downloads for Intel® NUC Kit NUC7i7BNH . To shorten the download process you can download here the Driver Bundle (a zipped file containing all the necessary drivers). Install first the Intel Management Engine Consumer driver and then the Chipset Device Software. Reboot the computer and than install all other drivers. The sequence now is not important and you don't need reboot your NUC after each driver installation. Using Intel Driver Update Utility is not recommended since it is not fully debugged. Install the drivers manually.
Once you will have your driver installed (at least the first two from my list), windows will update your drivers automatically.
I ended up getting all the drivers in the zip files via the IDUU, unzipping them and doing a manual install for all of them rather than using the IDUU. After doing that, the situation *finally* resolved itself. What a frustrating experience. I've built numerous PCs from barebones systems going back to DOS/3.1 days, and this has been the most frustrating of them all by far.
I have the exact same problem, but I received a replacement unit which exhibited the exact same issue so there is obviously a problem with this model and audio.