When attempting to retrieve a catalog object via “/v2/catalog/object/{object_id}” it appears that if an item is deleted this endpoint won’t return it, despite the object appearing in “/v2/catalog/search” when include_deleted_objects is true
That’s correct. The GET request for RetrieveCataloObject doesn’t have a parameter to set include_deleted_objects. Only the POST requests of SearchCatalogObjects and BatchRetrieveCatalogObjects allows you to include_deleted_objects. 