In uefi mode, the manufacturers uEFI firmware is responsible for all device support, so if the keyboard does not work, it's the Lenovo uefi software which needs to be fixed.
Maybe see if there are any updates available, or try plugging into a different usb socket?
Thank you for explanation.
As suggested, I have tried to plug in into different socket on docking station - still the same issue.
Tried on different docking station as well- still it is same.
Tablet has only one USB socket.
Did you check for a UEFI update? If you are in UEFI mode, then UEFI is responsible for the keyboard and mouse.