The most common reason for GCP accounts that appear 'Healthy' within the platform but fail to ingest Billing/Cost/Usage data is a misnamed 'Dataset' name, BigQuery table or 'ProjectID' within the GCP Project responsible for Billing/Usage.
If you configure a new account and do not see any Billing data after 48hrs please confirm your 'Dataset' name, BigQuery table or 'ProjectID' within GCP matches the GCP configuration within the platform -
Setup -> GCP Billing -> Edit Billing account
If you do update the'Dataset' name, BigQuery table or 'ProjectID' to match the GCP configuration, it will generally take another day of processing before you will see the information flow through to the platform.