I am a professional software engineer and it's my opinion that addressing this bug correctly is relatively straightforward. If you know the payoff date for the original loan and the origination date for the new loan, you can take a weighted average of the loan balances.
I invested a non-trivial amount of my time filing this bug report and identifying duplicates so that, as one software engineer to another, I could help the team at Intuit address this defect. It's disappointing to hear that they simply do not care to address it.
