S9 Filter issue, not fully cutting the sound

Hey,

I don't know if it's normal or not, but my filters don't totally cut the sound when I fully turn them to the left or the right, on both channels, so I can still hear the music.

I'm a bit surprised, as with my Rane 62 I didn't hear anything with the knobs fully on the right/left, it cut the sounds entirely. Is it normal on an S9? Does anybody else has this problem? Is it a problem with my mixer?

Thanks!