Version:
hasura/graphql-engine:v2.0.7

Steps to produce

1. Add a new mutation to remote schema(created with Symfony framework using GraphQLite) with the following input as an argument

input TestInput {
  client_note: String = null
  client_email: String = null
}

2. Reload the remote schema from console UI.

3. Open remote schema's permissions and add an arbitrary role like ROLE_TEST for example.

4. Click edit permission for that role.

5. The UI display the following input type, which doesn't have default values for its field

   

6. Select the previously created mutation then click "Save Permision"

7. The following error occurred.

   

When I inspect the request payload which contains the definition of the remote schema, I realized that it also didn't have default values for TestInput's field, which are null in this case.