Subscription does not trigger when using variable for mutation_in

[kbrandwijk]

What is the current behavior?
When you try to use an enum value in a subscription variable, the subscription does not trigger. In the playground, the subscription starts succesfully, but never gets any results.

Please share the relevant part of your project (GraphQL schema, functions, permissions, ...) for easier reproduction

type User @model {
  createdAt: DateTime!
  id: ID! @isUnique
  updatedAt: DateTime!
}

mutation{
  createUser{id}
}

If applicable, share the query, mutation or subscription for reproduction
This one works:

subscription{
  User(filter: {mutation_in: [CREATED]}){
    node{
      id
    }
  }
}

This one doesn't:

subscription($filter: [_ModelMutationType!]){
  User(filter: { mutation_in: $filter}){
    node{
      id
    }
  }
}

with variables:

{"filter": ["CREATED"]}

This one also doesn't work:

subscription($filter: UserSubscriptionFilter){
  User(filter: $filter){
    node{
      id
    }
  }
}

with variables:

{"filter": { "mutation_in": ["CREATED"] }}

What is the expected behavior?
The subscription is triggered in all cases.

[marktani]

This issue has been moved to graphcool/graphcool-framework.