Box 2 for 1098 has changed for 2019 where if the loan originated in 2019, then mortgage principal as of origination date is needed. Turbotax says to leave it empty.
"Box 2. Outstanding Mortgage Principal
Enter the amount of outstanding principal on the mortgage
as of January 1, 2019. If you originated the mortgage in
2019, enter the mortgage principal as of the date of
origination. If you acquired the mortgage in 2019, enter
the outstanding mortgage principal as of the date of
acquisition."