I am having identical problems on iPad Pro 11” on 14.2 ... With just a few percent remaining, the charging symbol will light temporarily (one or two seconds) when I plug in the cable, then disappears, often with the message “not charging”. That is, it recognises the USB cable has been inserted, but then decides it’s not going to charge using it. also get message about needing to unlock to allow usb accessories, even though it is unlocked. the only solution I’ve seen so far is to let it run to zero charge, and it powers itself off, and the charger will then work overnight (up to 100%). However, the battery is running down to zero on a daily basis. consequently, this feels like a software bug as it behaves differently when there is no op system to reject the charging.