Efiled 2019 and 2020 1040X Amended returns have been getting a message on the Where's My Amended Return Tool on the IRS Website:

Take Action:

Your Amended Return was received on April X, 2021.  However it has not been processed.  We apologize for any inconvenience.

Please call 800-829-0582.  Extension 623 between 7-7 M-F.  You will need a copy of your return.

I've checked and the March returns I submitted all appear to have gone through.  The April ones seem to be about 75% needing a call in to verify identity.  People phoning in just have to answer a few questions to verify identity.  2 days after verifying identity, IRS webiste still has not been updated, 2 days later.