If the "CustomDisplayTile" tag is enabled in entities supporting this tag, using some IDs containing block-form tile entities in the DisplayTile int will not come into effect, as a, ex: Minecart with the DisplayTile int set to 63, 68, or non-full blocks such as doors will render the block displayed, as I chose a sign (63), invisible. I debugged this using various ids in a NBT editor and some of the results are the same symptom I described above.