TurboTax reduces amount of cash charitable contributions (1040 Line 12b)

I am trying to complete our 2021 taxes using TT Deluxe.  We are married filing jointly. We had $1,000 in cash charitable contributions, which were entered correctly. When I review our return, we keep getting an error message regarding the amount listed on 1040 Line 12b.  It is showing a value of $300, but should be $600 per the instructions.  I can update the amount, but TT changes the amount back to $300 again, which reduces our refund amount.

 

The error message is as follows:

1040/1040SR Wks:  Charitable contributions:  Charitable contributions has an unacceptable value.