Long term stock sale with basis not reported to its

It depends.  You have two actions you can take that should eliminate this experience.

1. Delete the 1099-B and enter it yourself with the correct selling price and cost basis.
2. Try going to the field, using the delete key to remove the zero.
3. Once this is completed, and before you go back to enter the cost basis, please do the following.

In this situation, first please try clearing the cookies and cache.   It handles many issues that seem nonsensical on a regular basis. 

• Close your TurboTax return first.

Watch to be sure you are selecting 'all time' as example.  Do not use selections like 'last hour' for those browsers that give  you options.

• How to clear your cache

Once this is complete open your return and see if you are able to move forward.