I am using this documentation as a reference on how to associate a label to a user who is messaging my Facebook Page. https://developers.facebook.com/docs/messenger-platform/identity/custom-labels/

It works, but I'm receiving an error regardless. Here's an example of the response:

{'error': {'message': 'Unsupported request - method type: post', 'type': 'GraphMethodException', 'code': 100, 'fbtrace_id': 'AlX1zldzCBdHTpz-4YKlcSX'}}

I always receive that type of response no matter what. However, when I check my page's inbox, it does successfully add the specified label to the user.

Is this a bug?