Im having the same issue, and for me without rebinding the left click this device is not going to suit my needs.
I would like to see the feature available because the box says 8 programmable buttons, not 7.
I think removing the ability to rebind mouse1 should have never been approved as it falsifies every piece of specification and advertisement for not having 8 programmable buttons.
Im not being salty and i dont mean to post twice about this happening but i've been mislead by marketing to buy this product and as a consumer i deserve and have the rights to the product i purchased.