At this point, I can only recommend upgrading firmware on NUC. If that does not help, create a relative symlink on the TFTP server: /var/lib/tftpboot/EFI/redhat -> ../../grub2 to workaround the issue.
At this point, I can only recommend upgrading firmware on NUC. If that does not help, create a relative symlink on the TFTP server: /var/lib/tftpboot/EFI/redhat -> ../../grub2 to workaround the issue.