I know it’s been a year since you posted, but I have this same problem with my now retired air 2. (Which the wife now uses)
i found that that if I could position the adapter at the iPad just right, it was updated “connnect” and take a charge. It’s annoying, but it works…
I’m tempted to do a tear down on my own to check it out, see if something’s come loose but with the repairable factor at 2/10 not sure I wanna delve into a complicated repair.
dis you ever get this fixed? Was it the charging port itself? Something else?