Include option to turn on or off check marks in slicer so that users know what is and what isn't selected.
If this means : the slicer should indicate if a selection has been made or not so that the user will know this even if the current selection(s) are not visible on the list (because the list is long), then I agree. As is, the HMI and thus the particular sliced data set is not always clear to the user and they are likely to be forced to unselect all slicer selections to establish a new configuration. Optionally, the option to have a visual indication of 'slicer is using a subset' might be a configurable pararameter
