Why might the system not be liking that I'm trying to enter (3) 1098s for Mortgage Interest Paid? I can enter 2, but on entry of 3rd it suddenly cancels out any deduction

We sold our primary house in 2020 and subsequently purchased another after a job-necessitated move.  The new loan was sold/acquired by new lender, thus I have (3) 1098s.  As I'm entering them I can see the Fed Tax Due number decrease accordingly.  However, as I enter the 3rd I get midway through the addition and the system "breaks" and the Fed Tax due suddenly jumps back up to the number it was before I started entering any of them.  I've deleted them and retried several times, mixing up which two are entered first and it doesn't seem to matter which the 3rd is, just that I'm entering another.  Doing so cancels out any deduction I'm getting, so system is acting like I've not entered any Mortgage Paid deductions, yet I can see them there.  I can't figure this out.