I've got the same issue with the 787 downgrade. I was able to change back to First on the JAL website but having just spoken with AA, they are refusing to issue the new ticket. JAL is showing that they have issued the new ticket already.

The AA app is also showing the new flight details but when clicking on manage trip I don't see the details.

I guess I need to keep trying with AA until I speak with an agent who will process the change??