IPad Pro only charges through the Magic Keyboard or if i plug it in while off.
I recently noticed that my new 2020 IPad Pro 11" won't charge when directly connecting the usb-c port to the charger, though I can still charge the Ipad through the magic keyboard port. The usb-c port will notice devices plugged into the usb-c port such as a headphone adapter and a usb-c to usb-a cable to attach an audio interface.
I did notice that if I turned the ipad off and plugged in the usb-c cable the ipad would turn on and charge. If you would then disconnect and reconnect the charging cable once it was on, the ipad would refuse to charge and act like nothing is plugged in.
iPad Pro 11-inch Wi-Fi