I have set up a filter to select a date range. I define the date option as 'the date...' so the user can select a date from the calendar. I only want a date selected from the calendar, hence only one option enabled.
When the user populates the filter, they need to reselect 'the date...' (which is the only option) before the calendar appears. It would be better to have the default setting loaded already (in this case so the calendar opens when you click on the filter). If only one option has been defined, why do you need to select it first?!