The step-by-step help for Box 2 says "If you received a Form 1098 or similar statement from your lender, enter here the amount from box 2, 'outstanding mortgage principal.'", and that the worksheets will draw data directly from the 109 worksheet.
Entering an amount in the TT 1098 worksheet that's different from the bank's 1098 is another way to override the error--but the error is still there. Plus, it means the TT data won't match what's reported to the IRS. Moreover, the "solution" you suggest doesn't actually to the proration correctly, especially if the refi amount differs from the original mortgage's balance on the refi date (as happens, for example, if there are points or if closing costs are included in the refi amount). The amounts on the CA mtg worksheet come automatically from the 1098 amounts on the fed forms.
I can override the starting and ending balances on the California mtg int worksheet, but since the worksheet apparently ignores the "months" entry the result won't be prorated correctly either. Or I can do the calculation outside TT and enter the correctly prorated average directly as an override on the worksheet, which is what I've done until TT corrects its error. I note that correcting the error is going to require gathering more data in step-by-step, since for the moment s-b-s doesn't ask when a refinanced mortgage was paid off or the and so can't do the proration.
There are lots of us here in California who refinanced large mortgages in 2019, so this issue is definitely not confined to me.
