Deathadder V3 polling rate shows under 8k when 8k is selected

I have used Razer’s polling rate checker tool and found that if it’s set on 8K its nowhere close to that. what can i do to fix this issue? Also seems to be a noticeable difference to my in-game sensitivity. If its set to 1K, it will be a great deal faster than on the 8K setting for example.