I have found a thread that I think addresses this problem (that is, it's a TT BUG). Rather disappointing, I've used TT for over a decade and not particularly interested in switching if I can avoid it, but we're talking many thousands of dollars they're "costing" me with the system not working right.
https://ttlc.intuit.com/community/tax-credits-deductions/discussion/refinanced-mortgage-1098-messing...
