It's not conclusive, but it coincided with the removal of Office Beta. (yes, I know.)
Indeed, the ID shown is not the product key. It's quite different with -OEM- as part of the number.
MS has twice before confirmed my Key is correct. It's just that verification procedure won't work. If that other 'screen' did not jump over the required one, it might well work if I could only get to that button. As mentioned above, I tried racing to it, even stabbing at where I knew it was.
They're supposed to be phoning at 4pm Central today. One waits with baited breath.