the_terms is not displaying

I am customizing a copy of the Classic theme and need to add in a custom taxonomy list. I have copied over the exact code I used to have it show up on my desktop theme, but it doesn’t display anything. I put it inside the loop, under the title of the post.

Any suggestions?

<?php the_terms( $post->ID, 'custom-taxonomy-name', '', '', '' ); ?>

Thanks!!
Lisa B.

https://ww.wp.xz.cn/plugins/wpsmart-mobile/