vanbakoThanks for posting. I'll update the firmware as well and see what happens. If you will, please post again after you've tried it and I'll do the same.
I just got exactly the same issue with an UM425IA-AM005T
I shut down the laptop, connect power supply and it charges again, so it goes over 20% and I updated the BIOS to 305 (out today 8/31/20)
Hope the bios update solves the issue.