I've opened a support ticket, but wanted to see if there was any similar reports here.
Nuc11TNHi5 been using both Thunderbolt ports since I got the box in June with no issue, one as a sound card, and one as a 10Gb network adapter. Today they both stopped working and I can no longer connect anything to either port. Both devices work in another older NUC8.
I checked that the drivers were up to date, checked they were still enabled in the BIOS. Updated to the latest BIOS as the Intel updater suggested, and still nothing.
I assume they are fried, but just curious if anyone else has suffered a similar issue.
In case anyone else runs into this problem, Intel support came back and asked me to reset the BIOS to defaults which appears to have worked.
I hadn't made any change or update and it failed during normal use, but apparently there can be a 'disconnect' between BIOS and driver or something along those lines, which requires you to do a reset to defaults (none of the settings were changed in the BIOS previously).