You did enter the SSA-1099 here, right:
Federal > Wages and Income > Retirement > Social Security
But are you looking at the TT Income Summary? That only shows the gross figure, and is just FYI. The actual gross and taxable numbers are on Lines 6a and 6b of your tax return (and up to 85% is taxable.)
2020 Form 1040 (irs.gov)
