“A customer over paid on an invoice and it was marked to leave for use at a later time. Then a credit memo was created for the over payment”

That is the error. The overpayment already created negative AR. They just Doubled the negative.

“This was from a previous year so I […]

Resolution for 'created negative issue: 'How do I clear out the negative amount on the A/R Aging report?' available: Yes.

The created negative issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the created negative issue yourself by looking for a resolution described in the article. If it is a complex created negative issue or you are unable to solve the issue, you may contact us by clicking here or by using other created negative support options.

For more information about resolving issues related to created negative in Quickbooks/QBO or to get support for the issue 'How do I clear out the negative amount on the A/R Aging report?', click the link below: