The upper age limit of 70 1/2 for contributions to an IRA was recently removed (with limits on the amount). But TurboTax won't allow me to declare the contribution - ?

The elimination of the age limit for traditional IRA contributions applies to contributions for 2020 and beyond.  Eligibility to contribute for 2019 (even if the contribution for 2019 is made in 2020) is still subject to the original age restriction.