Google Maps now has better multi-window support if you were someone who has wanted to use this app while also using another app at the same time. Multi-window support for Maps is nothing new, but in an update for Maps that was pushed nearly a month ago, multi-window has been improved as it will now work and continue to update your location status and show you everything happening on screen graphically, whereas before it would stop working if you interacted with another app. It's not clear what exactly was causing the issue in the first place, but it now seems to have been fixed, though it is worth noting that things would work like they were supposed to before as long as when you opened up Maps in multi-window it was the most recent app you were using.
Since you had to use Maps last, this meant that you couldn't really use Maps with multi-window in the way the feature was intended because you couldn't actually interact with the other open app or Maps wouldn't update anymore. Now though, You can open Maps, then open another app and use it in multi-window while Maps continues doing its thing, or you can open up something like Gmail first, and then open Maps in multi-window, then go back to using Gmail while Maps still continues to update and do what it's supposed to.
If you don't use multi-window much or you never really used Maps with the feature, then this issue probably went unnoticed by you. For anyone that had used it and experienced the problem this is likely a welcoming revelation. As the update was pushed out nearly a month ago to users, everyone should already have it installed unless you don't update your apps very often. If you have your apps set to auto-update then you're likely already on the version where this fix was applied and you can use the app in multi-window accordingly without running into this problem. In addition to fixing this particular problem, Maps added new features not too long ago that further improve the app's usefulness. For instance, the app will now help you find parking spots in some cities, and even more recently it's now possible to add videos to Maps for places you've been to instead of just adding photos, which is not just a nice new feature for local guides, but also any other Maps users who are looking to find out more about places they want to visit.