Have you checked the FAQ?yes but 1440p is LOWER than 2160p !! It doesn't even handle 2560x1440p @60Hz and it's lower than 4K.
I thought that it could have been able to handle a higher refresh rate when a lower resolution was set.
1080p > 60hz,
That's it. It's the limitation, and you have to accept it as I do.
If you need a higher resolution with a high refresh rate, then go to buy a high-end gaming laptop like GE series.