A custom entity has been created but is not showing up as a reference entity in Site Studio, in the entity browser element.
Use case: You prefer to load entities by reference in a 'drupal-style' method, if Site Studio's 'custom element' interface feels limited.
Set the entity annotation flag
common_reference_target = TRUE
This makes the custom entity available to entity reference fields.
Re-save the Site Studio settings, styles and templates by running
drush cohesion:rebuild in the Drupal docroot using a CLI and clear Drupal caches.