Vehicle deduction is not calculating correctly

My vehicle expenses appear to be malfunctioning on the site. First of all, when it showed me what I had last year, everything was blank, and it is blank every time I go to make changes. That is obviously indicative of some larger problem.

 

I just enter mileage without itemizing, and I have some interest on the vehicle. My mileage was 8863 for 2020, which should work out to a 5,096 mileage deduction, and my interest in 2020 was 914, which should work out to roughly a $540 deduction ($914 x (8863/15000)). My total mileage for the year is about 15K, but I haven't checked that precisely yet. Thus, my total deduction for the vehicle should be roughly $5636 vs. the $1149 it is currently showing. Any idea what could be causing this problem? I am pretty sure everything else is entered correctly. Again, I have to re-enter everything when I go to make changes, which I know is not how that form is supposed to behave. I saw that some similar bugs were recently resolved, but my guess is other things got broken in the meantime.