I had the same problem in filing a late return for my husband.  This is a flaw in the Turbo Tax program imo, it doesn't check the date being filed vs year being filed when it comes to the CPP overpayment. 

We are sorry for your loss. Could you clarify if you are using TurboTax Online or TurboTax Desktop/Download? What year are you filing? 

Thank you for choosing TurboTax.