mongengine (.10.6) does not save the Document

Question

I have simple REST/json api. I am trying to update a mongoengine model Listing using a PUT call. I get one from the mongodb and update it using my own deserilize method with the incoming json. The update does not work as the json has a few DBRef and EmbeddedDocuments. The object does get updated with the correct values before the save is executed. There is no error but the object does not get saved. Any thoughts?

obj = Listing.objects.get(pk=id)
obj.deserialize(**request.json) 
obj.save()
obj.reload()
return obj



class Listing(): 
    name = db.StringField() 
    l_type = db.StringField( choices=listing_const.L_TYPE.choices(), ) 
    expiry = db.ComplexDateTimeField( auto_now=False,auto_now_add=False, ) 
    a_data = db.EmbeddedDocumentField(Media) 
    lcrr = db.ReferenceField( 'LCRR', reverse_delete_rule=3, dbref=False, ) 
    meta = { 
    'db_alias': config.get_config()['MONGODB_SETTINGS']['alias'], 
    'cascade':True 
    }