See IRS publication "2019 Instructions for Schedule D", page D-12 where the "Capital Loss Carryover Worksheet" instructions are. Those instructions specify for line 1 ("Capital Loss Carryover Worksheet, line 1"):
Enter the amount from your 2018 Form 1040, line 10, or your 2018 Form 1040-NR, line 41. If the amount
would have been a loss if you could enter a negative number on that line, enclose the amount in
parentheses
Thus, the amount on "Capital Loss Carryover Worksheet, line 1" can/will/should be a negative amount if "2018 Form 1040, line 10" would have been a loss if you could enter a negative number on that line.
And as I mentioned, that is how TurboTax Deluxe 2019 used to behave and automatically filling it in when transferring a 2018 tax return. However, after some recent update the behavior has now changed and I believe the new behavior is incorrect and is a bug.
