TV checkbox default values can't be unselected

Hi I have the following CheckBox TV. Using Evolution

Input Values:
Reason To Invest=={{reasonsToInvestWidget}}||News=={{newsCall}}

Default Values:
{{reasonsToInvestWidget}}||{{newsCall}}


I want both boxes to be checked on all documents by default. But if i then try and uncheck both boxes it doesn’t save. If I only uncheck one item this seems to work.

Any ideas?

Thanks

Ben