Hi,
The modifications were added in the 4.6.2 2 months ago. It's this entry in the changelog:
Seletable filters will now be automatically hidden from display when there is no value to select in them.
Note that this required the modification of the product / filter view file:
i.imgur.com/UVwGXGd.png
So if you have an override on it from an older version of HikaShop, you won't see any change.
You would have to add the changes in your old override, or delete the override and redo the changes on the new version of the view file as a new override.