Why does a new taxonomy term get created when I assign an existing term to a post?

Thanks to @Milo for the solution. I deleted all the defaults to condense the code, and then changed the ‘meta_box_cb’ parameter to ‘post_categories_meta_box’, and it did indeed give me a tag-style metabox. As an aside, that’s not exactly what I envisioned, so I ended up using CMB2‘s taxonomy_radio field to get what I was after … Read more

is_taxonomy is deprecated. What’s the alternative?

See Codex page for is_taxonomy This function is deprecated as of Version 3.0. Please use taxonomy_exists instead. wp_insert_term uses taxonomy_exists to check if the taxonomy exists. This means if the taxonomy is a registered taxonomy. (It would be odd if wp_insert_term only you allowed to add a term to taxonomies with existing terms 🙂 ) … Read more