How do I use the React-Relay @appendNode directive with Hasura's generated functions/schema?

I am currently trying to create an interface wherein a user is able to append additional metadata descriptors to an object while in a modal and need to reflect the results of this append elsewhere on the page. I am using react-relay with Hasura automatically creating a graphql schema/functions. I am currently trying to use the @appendNode directive to append the result of the following mutation to an existing edge with other present data so that it can be displayed to the user. The insert_dataset_metadata_one function returns just the metadata node that needs to be appended, so I put the directive between the function call and the fields to be returned from that node.

export const insertDatasetMetadata = graphql`
  mutation mutations_InsertDatasetMetadataMutation(
    $object: dataset_metadata_insert_input!
    $connectionIDs: [ID!]!
  ) {
    insert_dataset_metadata_one (
      object: $object
    ) @appendNode(connections: $connectionIDs, edgeTypeName: "dataset_metadataEdge") {
      id
      name: field_name
      value: field_value
      datasetMetadataId: dataset_metadata_id
      normalizedName: normalized_name
      normalizedValue: normalized_value
    }
  }
`;

On the TypeScript side, I call this mutation with the dataset object's relay ID (that is id; datasetId is the foreign key used in postgres to associate the inserted metadata with the object it's describing).

      const { id, datasetId, metadata } = dataset;
      // foreach over the metadata to get a data object and an if statement to test what needs updates and what needs inserts skipped for brevity
      commitMetadataInsert({
              variables: {
                object: {
                  dataset_id: datasetId ?? '',
                  field_name: data.name,
                  field_value: data.value,
                  normalized_name: data.normalizedName,
                  normalized_value: data.normalizedValue,
                },
                connectionIDs: [id],
              },
              onCompleted,
              onError,
            });

Strangely, this insert fails with the following error:

RRNLRequestError: Relay request for `mutations_InsertDatasetMetadataMutation` failed by the following reasons:

1. unexpected variables in variableValues: connectionIDs

Prior to adding the connectionIDs variable and the @appendNode directive, this mutation worked as expected, i.e. the inserted metadata was present on page reload; however, since I'm trying to avoid reloads, that isn't satisfactory. I've dug around and looked for resources inside/outside of the relay docs which could offer guidance on this directive but couldn't find anything to indicate what the cause could be or what to do in this scenario. I have confirmed that the id variable's value is what I expect it to be (i.e. the relay ID of the dataset.) What am I missing/doing incorrectly?