Deductions & credits

This is really horrible user experience. I have been waiting to file for weeks. 

 

It's also unclear what happens if you sold a home (with principal loan amount < 750k) and bought another home (with principal loan amount> 750k) and thus have two 1098s -- if there was a gap of a few months between selling and buying, how does the math work out for how much mortgage interest can actually be deducted?