Can't add facet to view

Using Facets 3x and when trying to add a facet to a view I keep getting the following error stopping a facet been added.

Message TypeError: Cannot access offset of type string on string in Drupal\search_api_glossary\Plugin\facets\processor\GlossaryAZAllItemsProcessor->supportsFacet() (line 126 of /var/www/html/web/modules/contrib/search_api_glossary/src/Plugin/facets/processor/GlossaryAZAllItemsProcessor.php).

At first I thought it could be an issue with search_api_glossary module but it looks like its failing before this within the FacetsFilter class.