Please make sure the HDMI cable you are using is a high quality cable and version 1.4. Besides this, It is important to use straight connection from the NUC to the TV.
I know this may sound very obvious but also check the input mode on the TV or test different HDMI connection on the TV. I personally have seen cases where one of the HDMI ports on the TV does not recognize the HDMI signal.
Kevin, thanks for the suggestions. I tried a different cable and it worked. The 1st cable I tried was a new Amazon branded cable. I guess I'll avoid Amazon branded cables from now on. The 2nd cable, the one that worked, was a generic brand cable.