I got fed up with the rejections (pun intended) for the same reason. But I had sent my 2019 paper return in last summer! Obviously they are still hanging around unprocessed. So I just couriered mine (2020) to Austin TX using FedEx. That is where expats have to send it if you don't file online. It was received by a human at their mail facility. I have proof!!
It cost me almost $35 as I live in the UK. Now I will wait to see if I get my 2nd stimulus payment as the TT update put in the form to claim it as a rebate on the 2020 return. So first I have paid for TT to be sent from the US via Amazon and that cost a fortune. I wish we could us online TT, it's really annoying and expensive. I think it might be time to find other tax filing software. OLT will let those outside the US file online with no problems.
