Ct with uninvoiced credit amount has no payments for said credit amount and I cannot find a way to resolve this

The client's billing page shows that they have an uninvoiced credit.  When I look at their transactions, there are no payments to match the credit. 

Reviewing the appointment status report, everything seems normal except for several sessions that note the fee amount as CR in the Uninvoiced column.  These sessions are also noted as unbilled in the Status column.  The CR amounts add up to the total uninvoiced credit amount. 

Their uninvoiced list in the client page shows unpaid sessions that add up to the uninvoiced credit amount.  When I view the details for the session, the fee is correct and it is correctly noted as Unpaid by their insurance.  Also, the Recent Activity shows that the billing type was changed (presumably from self-pay to insurance) in May, and that the service code was changed yesterday. 

In the Ct's page, when I click on "Unpaid invoices," it shows an empty list for unpaid by client.  When I filter by "unpiad by insurance," it shows me the list of sessions that note the credit.

When I create a statement for the client, it shows all sessions correctly with no extra credit, but the bottom has a list of the stated session repeated with the fee noted as $0.00.

When I click on the appointment on the calendar, it shows the invoice as past due and right underneath that, it says, "Uninvoiced Amount: $### CR Create Invoice" where ### is the cost of the session.  If I click on Create Invoice, it creates a new invoice for the session with the description as, "Fee Adjustment for the session on MM/DD/YYYY" followed by the cost of the session as credit "$###.## CR."  The total for the invoice is the fee of the session in negative with a balance of the fee as credit.

I have considered deleting the current invoice and creating a new one to see if that solves the problem, but am hesitant because the current invoice has been submitted to their insurance and payment was sent via paper check.  Thus, deleting it will cause discrepancy between our records and the insurance records.  Deleting the session and rescheduling it exactly the same would result in the same problem with invoice discrepancy.

I'm stuck since I cannot find where this credit is coming from.  There are no payments that match the reported uninvoiced credit.  Rather, the listed payments properly match up to the rest of the client's sessions.