This message was posted on behalf of Intel Corporation
In regard to your inquiry, as you mentioned before, Intel does not test and validate Intel® NUC on FreeBSD OS or True OS, as you can confirm on the following link:
What we recommend is basically what you did, which is the BIOS update to the latest version 0055.
So, in this case, in order to get further assistance to try to fix this issue, the best thing to do will be to access the forums or support department for that specific operating system:
For testing purposes, if you have the option to use Windows, that will be really helpful, because if the NUC does the same, then it could be related to a hardware problem.