Possible Bug charitable deduction

Filing Married jointly with Turbotax Deluxe with Charitable deductions over $600.  Review tab first changes the $600 charitable deduction to $300.  Then it flags the $300 as an error.  Correcting it manually makes the return correct again.   I noticed the bug because it took my refund down and then put it back up to the original amount after the manual input of $600.