I updated TurboTax and tried out 1099B import from TD Ameritrade with negative proceeds. Everything seems to be working and Smart Check gave me no errors.
A minor annoyance is that TurboTax rounds off before doing the subtraction to calculate gains. There is a rounding error on the total proceeds of $10 or so. That's the difference between TurboTax and the 1099B total proceeds. There is about a $13 difference on the total gain out of ~$8,250.
It is probably will not trigger an audit. But it is an annoyance.
