How do you bend on a neck rack?

I got something new in the mail yesterday, a Farmer Sidenote neck rack. It’s a cool little gadget, but I have an issue with it. When I try to play single notes, the magnet holder likes to push back. Causing my bends to sound very airy. It’s not because of my embouchre or my harps. When I take my Golden Melodies (both with Progressive and older covers) off the rack and lip purse, my usual embouchre, it sounds just fine. I’m a complete newbie to racks so I don’t know how to fix it.