Turbotax calculated cost basis but is telling me it can't for some. How do I find this?

Based on your question, I am assuming that this is for importing a cryptocurrency CSV file.   Are you unable to download the CSV file for cryptocurrency or for another financial item?   If you are having trouble downloading the CSV file for cryptocurrency I recommend that you request, if you do not already have one, Form 8949 from the institution you are trying to import from.  Delete all imported transactions, if any were actually imported, and enter the totals as a single transaction as shown on the 8949.  

You may want to attach a pdf copy of the 8949 to your return for verification purposes.

The IRS is concerned that you are properly reporting your total capital transactions with their associated cost basis and while individual transactions are important, the totals are the most important.

@afashoda