Welcome to the club...... TT has acknowledged that there is an issue and is apparently working on a "fix".
Given that most financial institutions has not yet provided 1099-Int & 1099-DIV and OID's, this is not as pressing for me. It is frustrating never the less to find a bug for a common scenario -- refinancing in 2020 was not a rare occurrence.
I was able to go into the combined "Ded Home Mort" worksheet and over-ride Line 12 to plug in the "average", which for me is original mortgage + new mortgage / 2. To override, highlight the value in line 12 use Menu-->Edit-->Override. You should then be able to plug a value.
This could be a fix for simple refinances. (Note: these worksheets do not go to the IRS)
Disclaimer: I am not a tax professional, accountant, etc - use at your own risk 🙂
