Just to clarify, with ALL StudioLive mixers, classic or AI, the scene shown on the scene menu at boot up is actually not showing what is currently loaded, or even what was last loaded. On the classic StudioLive mixers, what it is actually showing is just the last scene you had scrolled to in the Scene menu before you powered the mixer off.
Normally this is the last scene you loaded, but it's also possible to load a scene, scroll to a different location, and when you power cycle, it comes back up showing that scene you were on instead of the one you actually have loaded. The classic StudioLive mixers have always worked this way, including the 16.0.2.
The difference you are experiencing with the StudioLive AI is that it doesn't correctly show the last scene you had selected in the Scene menu before you powered off the mixer. It instead shows the Zero Out scene on the scene menu. It's actually an issue logged in our bug tracker to be fixed in a future release.
The StudioLive AI mixers have always worked this way though, so when you mention that you used to be able to power up with the last scene showing, I'm assuming you mean on a classic StudioLive mixer you owned previously. The StudioLive AI mixers have never done this, on any firmware version.
In lieu of a forthcoming firmware fix, I would suggest a few things to help deal with the issue.
First, I would recommend saving often, and always making sure to at least re-save the current settings to the appropriate scene before powering off, to make sure the scene is always up to date. When you go to save a scene on the scene menu, it will always start with the name of the last loaded scene (or the Zero Out scene if no scene has been loaded since boot up).
Second, I would recommend that upon power up the first thing to do would be to load the Scene you intend or need to use. If you re-saved it before powering off, it should be up to date, and once you load this scene, if you make changes and need to re-save it, it will already start with the correct name, allowing you to avoid having to enter the name again.
Doing these two things should mean that it won't matter what scene was last loaded when you power on later, because every scene should be up to date with the latest settings from that show or venue, and simply loading the scene you need will ensure you have the settings you expect, and that you're ready to re-save any updated settings as needed.