Clear Books thinks Bank charges is outside the scope of VAT

Trying to explain a payment to the "Bank charges" account can give a warning message if you don't set the "correct" VAT rate:

Clear Books thinks Bank charges is outside the scope of VAT. Please set the VAT rate to Exclude from VAT return. To ignore this warning resubmit this form.

Why exactly does Clear Books think that? This government guidance says that most financial services including "The operation of a current, deposit or savings account" is VAT exempt rather than out-of-scope.