Create two of the same slicers, making sure one of them (referred to as 'first slicer') only has 'interactions' with the other slicer ('second slicer') and nothing else on the page. Select the chosen items from the first slicer and it will filter the second slicer to only show those options available. Go to View->Selection Pane and hide the first slicer so it is no longer visible and you're sorted.
me too have the same problem.
solved temporarily with created double slicer (one on the top of the other)
but sometimes this slicer doesn't work (there's blank option in the slicer)
so i have to re-publish from desktop version to eliminate the blank
and it happens quite frequent
so please, Microsoft, would you fix this?