[Nokia 7 Plus Guides, News, & Discussion] valexbast:
Since we've been talking about Pie in at least four different threads, I thought I'd create a single one to address, list and possibly fix all the issues that are being experienced with the gradual release of Android 9 on Nokia 7 Plus. Mods: I'm assuming this is helpful, but if you think this thread is redundant feel free to delete it.

IMPORTANT: Before you do anything or think something is broken, make sure you restart the phone twice once you've installed the update. If issues are still there, you might go for a hard reset which is always helpful for creating a clean system environment.

In any case, you're welcome to add to this list and help others find solutions. This is what I found so far:

Battery draining

Most users noticed a decrease in SOT, for some this is even 2-3 hours less than on Oreo. While it might be peculiar to Pie itself, it is worth noticing that the new Adaptive Battery feature takes some time to adjust according to how you use your phone and learn what apps to handle and how. You should also check that no app permissions have changed since the update, or that no unwanted processes are misbehaving because of it (see below).

[MENTION=2125405]trveller72[/MENTION] points out a neat trick: deactivating the automatic Battery Saver (Settings > Battery > Battery Saver > UNCHECK "Turn on automatically") seems to extend battery life a lot.

Heating issues

Regardless of the SOT, these should not be there. I experienced the thing myself and in deep October no phone should burn into one's pocket, whether idle or when doing some light browsing. If you're having heating issues, this is most likely related to processes misbehaving and abusing your CPU when they shouldn't (either because of an application bug, or because of something gone wrong after the update). In this case you should launch the ADB command

adb shell top

which returns the CPU usage of your phone (make sure, of course, the phone is connected to your computer and has USB debugging enabled). This might give you an idea of anything strange going on and allow you to act accordingly. Or you could go for a hard reset like I did, which is a nice overkill solution and grants that you carry over no unwanted issues from Oreo - and it also recovered some SOT for me.

No adaptive brightness fade effect

I experienced this myself: the screen goes from 0 to 100 brightness in a millisecond and you're blinded forever, never to see your loved ones' faces again. This might possibly be an issue with the personal settings brought over from Oreo. In my case, I solved it to a degree by playing with the bar a bit, and it was solved completely with a hard reset. I think the fade effect is a bit faster in Pie anyway, so there is a degree of difference you should not worry about.

App notifications not disappearing

Notifications for some apps tend not to disappear when you swipe over them. For instance, this is true with the "HDR processing" progress bar of the PixelCamera mod (or better yet, in some versions of it). No fix for now, you just have to force quit the app and hope it is made compatible soon.

UI and Animation glitches

As with all first releases, this one is not perfect yet. I've personally encountered some animation glitches with the reception of nested notifications (especially in the lock screen), non-standard DPI settings, app-switch animations, volume control when writing on your keyboard, and minor stuff of the sort. While most of these are system-related and will have to be fixed in next releases, for in-app glitches make sure they are correctly updated and compatible with Pie; you could also try deleting cache/data, uninstalling and reinstalling them.

In particular, some report an issue where the bottom part of the touchscreen stops working after prolonged inactivity, regardless of the navbar settings. [MENTION=9089546]k3dar7[/MENTION] suggests using XDA Navigation Gestures (no root).

Digital Wellbeing

Yes, this is not compatible with Nokia 7 Plus yet, despite it being in DP4 (iirc), the feature is still unavailable although installed on the phone and already collecting data, and can be enabled by subscribing to the beta program (thank you [MENTION=4797097]divvykev[/MENTION]). Downloading it as an app from Play Store won't be possible, but [MENTION=5277966]Redcap56[/MENTION] kindly points out that a working version is available for download at APKMirror.

"Non-issues"

(i.e. things you're probably complaining about but are actually feature-dependant)

- The new gesture-based navigation is not available. It's there, but you have to turn it on under Settings > System > Gestures > Swipe up on Home button

- Mobile data is always active even when on a Wi-Fi. Yes, unlike before it is, but you can turn this feature off in Developer Settings.

- There is a maximum number of possible notification icons before the dreaded "etc. dot" appears. Nothing that can be done, unfortunately. This was decided by Google regardless of not all phones having a notch.

- File Manager is gone. And FilesGo is now there, like the child you never wanted. And most likely you never wanted it because it doesn't allow you to browse folders. The old file manager can still be accessed through the Download app or in System > Storage > Files. If you can't see the internal memory, make sure the option is ticked in the three-dot dropdown menu.