I don't have it either, but I have heard of it. It's something to do with the kernel not being set to allow the s2idle power level. I don't know what triggers it, but setting some kernel flag forces it to show that sleep level which will then be used for sleeping.

A such-afflicted laptop will be missing the s2idle that you see querying /sys here: https://www.togaware.com/linux/survivor/sleep-modes.html