Trigger or filter attribute - new value is empty or is not empty

Not sure if anyone else is having this issue. When adding triggers or filters to a Smart List and selecting a constraint of "New Value" and 'is empty" or "not empty" the field does not disappear. E.g. when adding a Data Value Changes trigger of "Email Address" and "New Value" to "Is Empty" we cannot save the Smart List as the Enter Email field does not disappear (it normally does when "Is Empty" or "Is not empty" is selected).

Help!