$push and $position operators do not work with list in embedded document

[tjhall13]

    class Author(EmbeddedDocument):
        name = StringField()
        genres = ListField(db.StringField())

    class Book(Document):
        author = EmbeddedDocumentField(Author)
        title = StringField()
        text = StringField()

    book = Book(
        title='Hello World', text='Lorem ipsum dolor sit amet',
        author=Author(name='John Doe', genres=['Mystery']))

    book.save()

    book.modify(push__author__genres__0='Fiction')

Running the above code results in the error:
mongoengine.errors.OperationError: Update failed (The field 'author' must be an array but is of type object in document {_id: ObjectId('5c087e326241ea797f8fab93')})

[erdenezul]

I am bumping 0.16.3 now @tjhall13

[tjhall13]

Thanks