You should always register custom taxonomies and post types to each other as early as possible. Wrap your registration process in a function, hooked to the
init hook at the default priority.
'taxonomies' => [ 'some_custom_tax' ],
// other arguments
If you like this question & answer and want to contribute, then write your question & answer and email to freewebmentor[@]gmail.com. Your question and answer will appear on FreeWebMentor.com and help other developers.