It seems I found a solution, based on several posts in the internet.|
Go into BIOS settings -> Advanced -> System Component, and set the following two settings to “Enabled":
S5-Charging Driver ... Enabled
S5 LPM Settings ... Enabled
It worked on mine; now, no matter when I plug in the USB cable, it will charge with 2.8A under running or standby Windows or Android, as well as when the tablet is shutdown.
Hope it helps you, too.