When the March update landed with the second Pixel Feature Drop, Google originally pushed out two separate images for the Pixel 4 series of phones: An AT&T-specific version, and another for everyone else. Apparently, the AT&T version didn't pass muster, as Google has pulled the update.
Anecdotally, we saw a few reports in the day following the initial release that Google Pay wasn't working for Pixel 4 and 4 XLs running the AT&T version of the update, but that isn't too unusual. Sometimes it takes Google a day or two to update certification details on its end so that Google Pay works, and this happens very often for Developer Previews/beta releases.
We reached out to Google to determine the precise cause for why the update may have been pulled, but the company did not respond to our inquiries. (Update: Following publication, a Google spokesperson reached out with information regarding the pulled update, included below.)
Whatever the explanation, and whether the Google Pay/certification issue is to blame or not, the update has been pulled and is no longer available for manual downloads at either Google's OTA or Factory Image sites. Note that the Pixel 3, 3a, and 2 are still missing images for some carriers as well.
The update will be rolling out again in the next few days
A Google spokesperson explained to us that the AT&T image rollout actually was a mistake, and the company wasn't ready to push it live just yet. Whatever the more precise technical cause of the delay, we're told that a new version will be available in the next few days.
Update available now
Google told us to expect its March update for Pixels on AT&T to be ready in another few days, and sure enough, it looks like everything we've been waiting for is available today.