Reporting error in Turbotax Basic

How do you report an error in the Basic version of Turbotax?  Errors on 1040-SR.  On line 12b program enters $300 instead of $600 (when filing as married filing joint).  This error can be manually corrected after review finds the problem.  However, the program leaves line 12c blank (should be adding 12a and 12b).  It does show correct amount on line 14 (which adds lines 12c and 13) but I'm afraid to submit my taxes electronically as line 12c being blank might cause IRS computers to reject return.

 

This is getting frustrating as I have all my documentation and my taxes are done but I cannot submit my return. I can't find anywhere on the website or in the program that allows you to submit errors you find in the program.