Turbo Tax program bug (?) associated with the $300 charitable Cares Act Deduction

I completed my taxes using the Standard Deduction. In this case Turbo Tax correctly inserts the $300 charitable giving (Cares Act) on Form 1040, line 10b.  NOW I go back into the return and check the box that asks Turbo Tax to change from using the Standard Deduction to recalculate everything using Itemized deductions.  It recalculates my taxes using Itemized Deductions BUT it does not remove the $300 charitable deduction on line 10b of form 1040.  I must go in a manually delete it.