Box 1e Form 1099-B is where the payer would have entered the cost basis for the items sold.
The box is blank because the payer did not have the cost basis for your items.
You will need this information to complete your tax return.
It is will be used to determine any gain or loss you may have on the sale.
This link How do I find a stock's cost basis? provides information on how to find the cost basis of stocks.
[Edited 03/11/2020 | 1:57 pm PDT]
