I've recently had unusual issues with the IRS, not unlike what you have had.
I don't know what is causing, what I fear is, an increasing number of internal errors.
In the last two years (and I'm 66 yrs old) I've had them miss a full quarter of tax filings, and told me I owed the entire quarter of taxes, even though my bank account showed the IRS receiving the deposits. I still had to prove it to the IRS.
I also received a letter saying the IRS never received my 2020, 1040 filings which I E-Filed. So, I had to send them a paper copy, and the E-Mail receipts for the e-file transmissions to TT and IRS showing they were received and accepted.
