Amplify Sort Direction with Sort Field Name

I am executing a GraphQL query:

export const userByName = /* GraphQL */ `
  query employee(
    $first_name: String
    $sortDirection: ModelSortDirection
    $filter: ModelUserFilterInput
    $limit: Int
    $nextToken: String
  ) {
    employee(
      first_name: $first_name
      sortDirection: $sortDirection
      filter: $filter
      limit: $limit
      nextToken: $nextToken
    ) {
      items {
        id
        employee_type
        first_name
        last_name
        createdAt
        updatedAt
      }
      nextToken
     }
  }
`;

When I execute this query, I get this error:

sortDirection is not supported for List operations without a Sort key defined.

I am executing this query using this code:

const userInfo = await API.graphql(
  graphqlOperation(employee, {
    first_name: name,
    sortDirection: 'DESC'
  })
)

I'm trying to retrieve data, but the above error arises. I have also tried removing sortDirection, but I just get an empty array as a response.