Why don't I get a mileage deduction on a car I stopped using in November? It initially gives me it, but disappears when I hit continue. If I lie about selling, it stays.

I have tried both ways. If I don't check that I stopped using the car in 2020 (in November), the glitch doesn't happen. If I *do* check that I stopped using it in 2020, it still tells me I get the mileage deduction *UNTIL* I hit "continue" on the Ka-ching page. Then it disappears. I hit *back* and it tells me I don't qualify for the mileage deduction. It doesn't tell me why. It shouldn't matter if I sell my car or not. I don't want to have to stop using TurboTax but I might have to.