I have same situation but the above advise is incorrect.
You need to enter the balance on loan when the new lender took over the loan.
look at the calculations sheet and you can see for yourself. IF you enter 0 it leaves you with a huge negative number, on line F5 of Home Mortgage interest limitation smart worksheet, just as if you leave it blank; look at sched A line 8 and you will see that interest isn't included meaning you get less of a return.
Based on worksheet you need to enter the balance when loan was sold so it calculates the correct amount of principle payment paid to new lender.
I entered correct number on smart worksheet line and not above where it asks for Box 2 $. This way it matches the 1098 at least.
I am still going to ask the bank to see if I can get a corrected 1098. If not then ill leave it as is because the numbers are right. If they correct it on 1098 then I can enter it in part for box 2 of 1098
