I am trying to retrieve data on my domains using the API
https://gmailpostmastertools.googleapis.com/v1beta1/domains/mydomain-example.com/trafficStats?pageSize=100&alt=json

For a number of them data is successfully returned, but in some cases all i’m getting is an empty object.

Is there any way to make API return the same information that I see on the panel?

I expect at least some data since the metrics are not empty on the Postmaster panel.