When a channel customer's bills are processed through Partner Generated Billing, the process is as follows:
1) CloudHealth collects a copy of the Payer Cost and Usage Report (CUR) at the Partner level
2) PGB will extract the line items - minus tax and credits - belonging to each customer (as per their Billing Block configurations) and collect these in a file.
3) PGB will apply any pinned credits and Partner Billing Rules.
4) PGB will apply any Custom Pricebooks and create a final version of the PGB customer CUR.
5) CloudHealth will create an RBD file from the PGB CUR. This RBD is then used to populate Cost/Usage reports.
Note that this process generally takes 24-48 hours to complete so channel customer data is usually 24 hours behind the partner customer data.