Sounds like the cap loss carryforward did not transfer correctly from the prior tax year ... so if that is true then you must amend the return.
To see how to amend your taxes, click here:
Steps to amend in TurboTax
How to file amendment
Any calculation errors on the part of TurboTax are covered under the Accurate Calculation Guarantee. TurboTax will pay any penalties and/or interest due to a calculation error but not any taxes owed. The Guarantee does not cover any user entry errors or omissions.
See this TurboTax support FAQ for the 100% Accurate Calculation Guarantee - https://ttlc.intuit.com/questions/2566201-what-is-the-turbotax-100-accurate-calculation-guarantee
See this TurboTax support FAQ for submitting a claim - https://ttlc.intuit.com/questions/1901269-how-do-i-submit-a-claim-under-the-turbotax-100-accurate-ca...
See this TurboTax support FAQ for documents needed to submit a claim - https://ttlc.intuit.com/questions/1901060-what-documents-do-i-need-to-submit-a-claim-under-the-turbo...
