Air France phone customer service rep insists printed bag claim number is incorrect

Checked a bag with Air France in Barcelona, for trip BCN-CDG-IAH, got a printed receipt attached to the back of my boarding pass. Shortly after, got notice the flight was delayed by hours, so at my request, Air France rebooked me on American Airlines.

I specifically asked if my bags would be transferred from AF in Barcelona to AA, and I was assured they would be. You can guess what happened.

I tried making a claim on the website, but it has been down for going on five hours now. Finally got a phone customer service agent, but she insists the baggage number on my baggage receipt is incorrect and AF does not have my bag in the system. I gave her my booking reference number as well as the baggage receipt number. She found my reservation, but claims there is no baggage number attached to it, despite what I can see and touch on the back of my boarding pass.

AA can't find it, either, and does not show that the bag was ever transferred to them from AF. Neither airline will give me a PIR because neither is taking responsibility for possession of the bag at any point.

How can the baggage claim number be invalid? How do I get through to someone who can at least start the process of locating the bag, instead of telling me it doesn't exist?