Steve says,

"Yes, running a day end as of 2020 would "fix" the problem, but it would move all paid transactions to history for all customers, so this is not a good solution."

What if I waited until our next Month End (Period End) and right after that is complete, open OE and change the date to the same date of the Invoices and Credit Notes in 2020. Then run a dayend in OE. This way the paid transactions would already be moved to history because of the period end.

Would this work?