Error with taxonomy field query

[alancwoo]

I have a custom post type Document with an ACF taxonomy field document_types which is populated by a custom taxonomy Document Types. All are enabled and labels set correctly in my theme.

When I try to query this field like so:

query NewQuery {
  documents {
    nodes {
      id
      title
      document {
        documentType {
          ... on DocumentType {
            id
            name
          }
        }
      }
    }
  }
}

I get the following error:

"Abstract type TermObjectUnion must resolve to an Object type at runtime for field Document_document.documentType with value \"instance of WPGraphQL\\Model\\Term\", received \"null\". Either the TermObjectUnion type should provide a \"resolveType\" function or each possible type should provide an \"isTypeOf\" function."

Data is returned alongside the errors, but the field returns null even when something is indeed set in the field. Am I doing something wrong with the query?

---

Wordpress 6.1
ACF Pro 6.0.4
WP GraphQL 1.12.2
WPGraphQL for Advanced Custom Fields 0.6.1
WPGraphQL WPML 1.1.0
WPML Multilingual CMS 4.5.13