I also have 570 and 971. 570 dated 3/19 and 971 dated 3/26. I had to ID verify around 2/26. I called the IRS last week Friday for an update. I was told that the 971 referred to the ID verification even though the 971 posted to my transcripts weeks after I received my ID verification notice. Not sure if that’s accurate or not, but that’s what they told me.