I've sold vested RSU shares and they are reported in a 1099-B. Why doesn't my 1099-B report how many shares were held for tax paying purposes?

All of my vested RSU shares were sold and converted to cash.  I know tax was withheld since I have less than the total number of shares x market price at settlement.  Unfortunately the 1099-B mentions $0 taxes under Box 4 (Federal Income Tax Withheld).  Where can I find the number of shares held for paying taxes on a 1099-B?