I bought the OEM quickshifter for my 2018 R6 and installed it myself. I can't remember where i read this but it said try holding the shift lever with your hand with more pressure than you can do it with your foot. I did it with my hand and the QS light came on at the first attempt. I managed to switch it off and turn it on again.
So people who struggle with the foot try it with the hand and put more pressure!