Hi,
Now with the new vector icons in Office 365 the Slicers icon in Excel doesn't change any more.
You can't see if you have applied a filter to the Slicers or not.
In previous version the filter icon was "light gray with a monochrome x" when no filter was used and marked in "dark gray with a red x" when you used the Slicers to filter the data.
With a lot of Slicers, it is hard to see when the Slicers is used or not.
Regards,
Anna-Karin