T-Mobile has temporarily halted firmware updates for both its LG V30 and LG V30 Plus as of May 12, after initially launching the update on May 7. Specifically, this was the update bringing the handsets from Android 7.1.2 Nougat to Android 8.0 Oreo. However, the bugs behind the suspension of the update have still not been clarified, as of this writing and it's not apparent when the update might start rolling out again. Historically, similar holds have lasted up to a month where T-Mobile is concerned, so it wouldn't be unreasonable to expect a delay of similar proportions. In any case, the suspension comes just under a week after launch. So whatever the problem is, at least T-Mobile caught it fairly quickly.
In the meantime, the other major mobile carriers in the U.S. have already rolled out the Android 8.0 Oreo update to their own versions of LG's V30 without issues. Bearing that in mind, this problem might come down to some inconsistency between the software for the LG V30 and V30 Plus or with carrier added tweaks to the OS. As for what the new build is expected to deliver, Oreo includes the new optimizations and improvements baked in by default by Google. It also includes several A.I. features brought over from the LG V30S ThinQ. That means improved camera capabilities based on A.I. algorithms, among other smaller features. Beyond that, the Android Security Patch is reportedly expected to hit April 2018 with the update, according to users who have installed the OS for other carriers.
As noted above, there's currently no way to know for sure when this latest update might begin to roll out again or why the rollout was halted. Once it does resume, thankfully, it should also be rolled out to users who had already installed the presumably faulty short-lived version. Setting all of that aside, it's worth pointing out that T-Mobile's official site for the update actually contains a typo - as confirmed with GSMArena by the company. It correctly states that the update was launched on May 7 but the hold date was input incorrectly and is marked at May 2. That should read May 12.