You will need to wait until your return is either rejected or approved.
If it's rejected, you can return to the program to add the new 1099 DIV while fixing the error.
If your return is approved, you would need to amend it. As IRS is still updating the electronic version of the amendment form, you can't use the program to amend yet. Please come back later to this link 2019 Amend. If you do need to amend, please wait until your return is fully processed and you have received your refund or your payment has cleared.