Good afternoon, @smorgan01.

I appreciate you coming back and giving us some more details on this issue.

Based on the information you gave, I'll ask some additional questions to ensure we narrow down the cause of the problem in the system:

• Has the transaction ever been edited? (For example, create an invoice and record the payment, came back and edited the invoice or payment) This could be why as it could break the link between the two.
• Are both of the Sales Order's associated the same customer? If so, resorting all lists could help or creating a new customer and merging it with the old one (perform a backup first).

Please come back to send these details over. I'll be right around the corner!