It appears to be MB dependent in some cases as a few just fail in that mode.
I mentioned in another post that the MB-PSU will drop STR +5 standby if there is a sudden "large" load shift on the standby +5V rail. That’s easy to verify by looking at a USB hub that has a power led or connecting a led indicator to the 5V STBY line and seeing if it stays lit in sleep mode. Normally if hybrid-sleep mode fails it brings up the delete config message at boot. The obvious: default power button action = sleep.
I never managed to get mine to work in that mode but others with the same MB have, so drivers and SW along with USB hardware/drivers all seem to impact.