A person in another forum pointed us to this new FAQ, which acknowledges the problem, but punts the solution. The link: <a rel="nofollow" target="_blank" href="
https://ttlc.intuit.com/questions/4732918">https://ttlc.intuit.com/questions/4732918</a>
The text:
403(b) and 457(b) Catch-up Contributions
403(b) and 457(b) plans offer special catch-up contributions beyond the IRS's $6000 catch-up contribution for those over 50.
Unfortunately, TurboTax does not support the additional catch-up contributions associated with 403(b) and 457(b) plans. The maximum contribution TurboTax allows for 403(b) and 457(b) plans is $18,500 for taxpayers under 50, or $24,500 for those 50 and older.
Roth contributions to 403(b) and 457(b) contributions are supported by TurboTax.
Workaround
Customers who have 403(b) or 457(b) contributions above TurboTax's limit will need to paper file.