I just got this mouse, and wanted to describe what is happening to me, and see if it was what was happening to you? Basically, while in-game, the mouse 'forgets' the profile settings (even "Default" that has been changed), and goes to the out-of-box Defaults instead.
The mouse is still (wirelessly) connected to the PC, and all default buttons work. The software sees it 'normally', but any adjustments won't change the out-of-box Default that the mouse is stuck in. Turning it off/on then loads the user-defined defaults.
I bought this yesterday and it has done this to me twice today, and it looks like it'll be going back to the store.