Is "cash in lieu" on a 1099-B the same as a sale of shares?

Yes,  Cash in Lieu is considered the sale of shares. Instead of giving you fractional shares the company gives you cash for the factional amount.

You need to report this amount on your tax return, the cost basis in these shares is often $0.

Report this amount in:

• Wages & Income
• Investment Income
• Stocks Mutual Funds, Bonds, Other

some brokers like Schwab do  a cost allocation for the fractional shares sold.  use what's on the 1099-B unless a signifcant amount of sales without cost.