Django push notifications: InvalidRegistration with correct registration_id

Question

I'm trying to send push notifications with my Django App and the library django-push-notifications to specific Android devices using FCM.

I always get the same error:

{'multicast_id': 7577544316157180554, 'success': 0, 'failure': 1, 'canonical_ids': 0, 'results': [{'error': 'InvalidRegistration', 'original_registration_id': <token>}]}

I'm using a registration_id provided to me from an actual Android Device. I've tested that registration_id using the Firebase dashboard to send a test message and it works perfectly there. But my Django request never works.

Is there anything else I'm missing from configuration? Do I need to enable something else to be able to send the push from besides the test tool of Firebase?