I have the same issue. I mailed the paper file on 3/3/2020. USPS tracking showed "Your item was delivered to the front desk, reception area, or mail room at 11:53 am on March 5, 2020 in AUSTIN, TX 78710.". and IRS website showed no information. I don't even know whether the IRS received my file or not.
If the IRS sends a letter back to me, what address they will use? the address on my SSN or the address on my 1040 paper mail?
