local token-tree-link template not being found

Problem/Motivation

A local token-tree-link.html.twig file is not being picked up. Other templates are being picked up.

Steps to reproduce

Copy token-tree-link.html.twig from token template directory to our theme template directory.
Modify local copy (eg add a class) .
Clear cache.
Reload Form page which has token tree element:

    $form['xxxx']['token_help'] = array(
      '#theme' => 'token_tree_link',
      '#token_types' => array('comment', 'node', 'user', 'term'),
    );

Inspect page - 'modules/contrib/token/templates/token-tree-link.html.twig' is being used.

Proposed resolution

This could be down to the content of the '#theme' value in the code - but not sure how to get it to point to my version of the template.

Remaining tasks

User interface changes

API changes

Data model changes