No Custom Field Groups are displayed in the Toolset -> Custom Fields menu

Symptoms

This is an edge case that happens with Types 3.0 only if the site has a custom taxonomy with the slug filter. As a consequence, the listing page of custom field groups doesn’t show any items, even though all field groups themselves keep working normally.

Full explanation:

There is a surplus, 'filter' => 'all' argument, which is not recognized by a WP_Query and does no damage unless there is a taxonomy with a slug “filter”. If there is such a taxonomy, the WP_Query starts filtering by the term “all”, which obviously excludes all custom field groups from the results.

Workaround

The issue will be fixed in the upcoming release of Toolset Types.

As a workaround, you can download this patch and replace the custom_fields.php file found in the wp-content/plugins/types/application/controllers/page directory.