Strange behaviour with Fable to Javascript Bindings

I have the following javascript

//file1.js

class MyClass {
  constructor(name) {
    this.Name = name;
  }
}

function callMeBack(callback) {
  let v = new MyClass("MyName")
  callback(v)
}

export { callMeBack };

and the relative Fable JS bindings

//Bindings.fs

type I =
    abstract callMeBack<'t> : callback:('t -> unit) -> unit


module Binding = 
    [<ImportAll("./file1.js")>]
    let mylib: I = jsNative

Then I use the bindings in an application, calling javascript twice but with different F# types (class and record)

type MyClass(name: string) = 
    let mutable _name: string = name
    member __.Name with get() = _name and set v = _name <- v

type MyRecord = {
    Name: string
} 

let fClass() = 
    Binding.mylib.callMeBack(fun (v:MyClass) ->
        let name = v.Name
        printf "%s" v.Name)

let fRecord() = 
    Binding.mylib.callMeBack(fun (v:MyRecord) ->
        let name = v.Name
        printf "%s" v.Name)

Problems:

• Different results between class and record
• With class the result is wrong

Questions

1. Why this happens?

2. How to obtain the correct result with class type?