The Customer Status field showing in the Customer List is triggered differently depending on the way Partner Generated Billing (PGB) is configured for the Customer.
Customer Status will move to "Account Warning" based on these criteria:
Standalone or Consolidated: Individual account assignments are made in the billing block(s). Only those accounts that are assigned to a payer will be scanned for Status. When any account assigned in the billing block goes to Warning or Critical, the Customer Status will move to Account Warning.
Full Account Family: For this configuration we only check the Billing Account status itself as we include all linked accounts within it. Customer Status will only move to Account Warning if the Billing Account goes into Warning or Critical.
To summarize, Billing Blocks where accounts are specifically assigned are checked for status and will flag those that are in "Critical(Red)", "Warning(Yellow)", or "Not Configured". For Full Family we only warn on the Billing Account.