Informed Delivery has only caused me issues.
There have been many instances similar to yours where it shows an item of mail that does not arrive.
I end up trying to find the missing item only for it to be delivered 2-3 days later having wasted a couple hours of my time.
Once it was my son's passport. Lots of time on the phone with the state department only for the passport to arrive 6 days after the scan.
Once it was a check I was expecting. Again lots of time on the phone only for it to be delivered 3 days later.
My informed delivery email yesterday included a paid advertisement from the the U.S. Treasure Dept saying that the stimulus was on the way, not an actual scan of the envelope.
View attachment 550492
Did you have this notification or a real scan of an envelope?