This problem is back after an update to the software dated Oct 8, 2021.  I have been creating Transaction Statements for my client who has multiple customers with separate locations.  The structure is parent customer with sub customers "billed with parent"

All of a sudden on Oct 8, we are no longer able to perform this task.  We are receiving the same exact error message shared in this thread.  

The work around of saving customers an "billed with customer" rather than "billed with parent" is not an option because we have been operating this way for years.  When we attempt this, we get the following error, "You cannot change who this customer bills with because there are invoices for the parent that include charges for this customer, or there are payments from the parent that pay off invoices for this customer. Delete all payments or invoices to this customer's parent which link to this customer." 

I have had a chat with support on Oct 8, and I have not heard anything back about a solution.  I was told that I would be kept up to date on the ticket - which was submitted to engineering by the support specialist I was chatting with. Thank you for sharing this with engineering again.