I appreciate you reaching out to the Community. I'd be happy to give you a hand with this.
In QuickBooks Online (QBO), the open balance section on your supplier screen composes of the total amount of bills/payments as well as the overdue that was created on that specific supplier. What you've described can happen when:
Bill payments that aren't applied
Journal entries aren't being applied
Supplier credit that aren't being applied
Floating credits on a supplier can affect the numbers as well.
For further assistance, I recommend contacting our phone support team using this link.
Need QuickBooks guidance?
Log in to access expert advice and community support instantly.