Hi @mijo,
Welcome to the Auth0 Community and thank you for your post.
Since you are getting an Access Token, but it’s missing the payload this means that you are receiving an opaque token. Please make sure that you are passing the correct audience when making the request to the /authorize endpoint, as mentioned in our Get Access Token documentation.
You can refer to this community post or this Knowledge Artricle as well.
I hope this helped.
Best regards,
Remus