iPad Pro and Magic Keyboard together. The ”charge-thru” port doesn’t charge the iPad. H

When connecting the charge cable (with an adapter) into the port on the Keyboard, it first looks like charging started, but right after There is a labe ”Not charging” above the battery symbol.

Same hardware connected to the iPad port, no problems. The trouble is, that the Keyboard would be more suitable due the height of the port right at the table.

How much amps should be connected thru the Magic Keyboard port, to be able to charge thru it?