Background colour conditional formatting in slicer is acting weird

[Capstone]

I'm trying to incorporate background colour conditional formatting on the PBI slicer visual. If a value in the slicer is selected the background should change to grey else the default is white. But its acting weird. The background doesnt change when I select a value but when I copy the slicer the background changes in the copied slicer. Anyone having the same issue ?

My DAX is

Calendar Year_Slicer background colour =
VAR _count =
    COUNTROWS ( DISTINCT ( 'Calendar'[CalendarYear] ) )
VAR _countall =
    CALCULATE (
        COUNTROWS ( DISTINCT ( 'Calendar'[CalendarYear] ) ),
        ALL ( 'Calendar'[CalendarYear] )
    )
RETURN
    IF ( _count = _countall, "#FFFFFF", "#CCCCCC" )

I have tried using ISFILTERED as well but to no avail.

Im using May 2021 PBI version. Tested it on another computer with same version and same results

video 

[v-chuncz-msft]

@Capstone 

This is by design.

The source visual doesn't filter itself, it filters other visuals (target visuals).