Update: Within 1 hour I got the notice from Intuit that my amended federal return has been accepted, so I think my 2021 tax saga is over. The IRS can still get in touch if they think there's a mistake somewhere, of course, so I'll save all my records just in case. Here's hoping they just sit in a drawer/hard-drive unneeded.
If anyone else is still waiting to eFile rather than having paper filed, go ahead and give it a try again and I hope it'll work for you.
