Calling Cyanite.ai graphql from go lang returns 422 unprocessable entity

Question

First of all I am new to using graphQL in Go. I am using it to communicate with Cyanite.ai to generate metadata about songs. I am successful in asking an upload link and uploadId using graphQL and subsequently uploading the song. the next step is to turn the uploaded song into a Cyanite library item using a graphQL mutation with the uploadId that was sent to me in the first graphQL mutation call. From the documentation the GraphQL to turn it in to a library item is:

mutation LibraryTrackCreateMutation($input: LibraryTrackCreateInput!) {
  libraryTrackCreate(input: $input) {
    __typename
    ... on LibraryTrackCreateSuccess {
      createdLibraryTrack {
        id
      }
    }
    ... on LibraryTrackCreateError {
      code
      message
    }
  }
}

with variables:

{ "input": { "uploadId": "change me", "title": "API Track" } }

I turn this into the following struct for the graphQL client (github.com/hasura/go-graphql-client):

type LibraryTrackCreateMutation struct {
    LibraryTrackCreate struct {
        Typename            string `graphql:"__typename"`
        CreatedLibraryTrack struct {
            ID string `graphql:"id"`
        } `graphql:"... on LibraryTrackCreateSuccess"`
        Code    string `graphql:"code ... on LibraryTrackCreateError"`
        Message string `graphql:"message ... on LibraryTrackCreateError"`
    } `graphql:"libraryTrackCreate(input: $input)"`
}


var libraryTrackMutation LibraryTrackCreateMutation
        

with variables:

variables := map[string]interface{}{
            "input": map[string]interface{}{
                "uploadId": uploadId,
                "title":    title,
            },
        }

I execute the mutation with graphQL client as follows:

grapQlError := graphQLClient.Mutate(context.Background(), &libraryTrackMutation, variables)

which returns the error:

Message: 422 Unprocessable Entity, Locations: [], Extensions: map[code:request_error], Path: []

When I execute the mutation in a GraphiQL graphical interface on the specific song uploaded the result is successful. Is my syntax incorrect for describing the mutation?

I tried changing the syntax, but since im no graphQL expert these were shots in the dark. I tried it on other mp3 files with the same result.

On a successful run the Cyanite.ai graphQL server should return

{
  "data": {
    "libraryTrackCreate": {
      "__typename": "LibraryTrackCreateSuccess",
      "createdLibraryTrack": {
        "id": "21999304"
      }
    }
  }
}