"was rolled over into another IRA"

The loan isn't likely from any sort of IRA. Your taxpayer had some sort of employer plan account. What is the account type, specifically?

From: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-loans

"IRAs and IRA-based plans (SEP, SIMPLE IRA and SARSEP plans) cannot offer participant loans. A loan from an IRA or IRA-based plan would result in a prohibited transaction."

The timeframe to repay a loan when they leave their job still owing, was extended by the 2018 Tax Reform law, until the due date of the tax return (including extensions) so that a person leaving a job has more time to repay 401(k) loan.

The rollover, by depositing (repaying) all or part of the loan’s outstanding balance to an IRA or (new employer) eligible retirement plan by the due date (including extensions) for filing the Federal income tax return for the year in which the loan is treated as a distribution, will reduce the amount that was "distributed" by the prior employer to apply against the unpaid balance. This rollover is reported on Form 5498. So, get a copy of that form or the account statement which proves the taxpayer did this part correctly and timely.