The exact same thing happened to me, I added my own (new) card for billing and they immediatly locked my account and requested the docs, I got the same screen you described.

I had just moved countries and none of my new accounts had statements yet, by the time I got them I just get stuck in this repeat loop of upload docs, wait a few days, says invalid.

No way to get back in, all my purchases lost, no human to contact, I just don't use Amazon anymore. Very annoying