When I click the special thumb button on the lowest left part of the mouse it triggers Mission Control.

When I am in Mission Control the horizontal scroll wheel should be able to change desktops.

It works when I want to change to a left hand side desktop but when I scroll to change desktop to the right hand side one it bounces back to the screen I started from.

So the issue is that I can't change desktop to the right hand side one using horizontal scroll wheel while in Mission Control.

When I am in a desktop (not in Mission Control) changing desktop works both ways using the horizontal wheel.