Python Function call issue ( General )

I have to to call my update chat task in sync/async way based on a flag variable. I have a code something like this:

class UpdateChat:

    def __init__(self, is_async=True):
        self._async = is_async

    def update(self):
        parse_call = self._parse_async if self._async else self._parse_sync
        parse_call(utterance,dynamic_concepts,cache_id_str)
        # This should have ideally mapped correctly with function parameters of _parse_sync & _parse_async
        # But somehow: 
        #  - utterance is being mapped with dynamic_concepts
        #  - dynamic_concepts with  cache_id_str
        # cache_id_str not being mapped at all
     
     def _parse_sync(self, utterance, dynamic_concepts=None, cache_id_str=None):
        pass
        
      def _parse_async(self, utterance, dynamic_concepts=None, cache_id_str=None):
        pass

The update function is not mapping the parameters being passed in parse_call correctly( as mentioned in the comments above)

Two Questions, If i may:

• Why is this happening?
• Is this correct way of implementing such features ( from a design pattern perspective? ) Should we use Interface ( Python ABC ) or something else insead of mappings like this?