There is a known problem with Home Mortgage Deduction. TurboTax is working to fix the problem and the many other issues. There are many changes due to the CARES Act that require software upgrades. We have not been given an expected date for the fix yet. Please check back often to see if you can file your return.
In the meantime, you can try this work around. You did not provide the details of your Mortgage situation and therefore I am giving you a general work around that might help. Please try this.
If there is a refi and there was an outstanding mortgage principal listed in both of them on Line 2 on the 1098. When you do put an outstanding balance in both forms, then the program adds them together and if that number is greater than $750k, then it puts you in the category to "limit interest". To get that to go away, you need to go back to the deductions section and click on "edit" mortgage interest statement. Change the line 2 of the mortgage that you no longer owe on (like the one that you refinanced and paid off) to a 0 (zero) because you have refinanced out of that loan and no longer have an "outstanding mortgage principal". Once you change one of them to zero (the one that was paid off by the refinance) then it should no longer pop up with that error at the end when you go to file.