billykac,
I have a strong lead - a new lead not mentioned before on any of the forums I could find - as the cause of the problem.
I should first say that my Google Pixel 2 XL is fantastic. It works flawlessly. It is VERY fast. It is VERY seamless among the Google apps. This has opened my eyes greatly to all of the "overhead" on the Note 8 between Verizon's tinkering and Samsung's tinkering. The Pixel is pure Android. And pure Android has gotten really good all on its own as we have hid behind the mask of the Notes over the years.
I am not going back. I actually and unexpectedly fell in love with the Pixel XL. However, I was going to give the Note one last shot to pinpoint where things go wrong before I sell it on Gazelle. So I factory reset it. I allowed it to update itself without touching it. When it was done, I set the Google play store to not auto-install.
As the last few days went by, some of the baked-in apps had updates. I would update the app and it would install flawlessly. To me, this means I would not have any of the other phone issues discussed in this thread that accompanied the "download to 100%" but would not install" issue.
Then, today, I had a notification from Samsung. It asked me to allow auto-upload of Security Policy Updates. This is a Samsung notification. You can find it after the factory reset by going to Settings; "lock screen and security";"other security settings";"security policy updates"; "auto update"; and it will open a window. NOTE: It will show you the following screens once, and once you agree, they don't come back. I say this in case you can't find the language I am about to write below. Factory reset your phone and then do it. You'll see it.
Anyway, it says "SE for Android protects your phone and information by preventing flawed or malicious apps from bypassing security features". It then wants you to allow auto-updates. There is also a "learn more" button. I pressed it. The photo is attached.
Take a look. If this is auto-updating without notice, it can explain why some folks all of a sudden get the issue. The service can detect and delete downloaded software. If this is the case, this can explain why the apps download - but then will not install. I think its a real possibility that the Samsung Policy Updates or that service in general is stopping apps from installing. And when that happens, it freezes phone processes and that is causing the other issues as well - - or - - the other issues are being caused by whatever processes rely on this Security service.
Even more interesting is the data the update service collects. It collects your device unique identification number. in addition to everything else. I suppose this might explain why the issue follows certain people. I believe a strong possibility exists that most people do not have this issue because they have a "clean" Samsung string of computer code (can't find a better way to describe that in layman terms). What I mean is, a potential fix would be to exchange the device under warranty to get a new device with a new unique identification number, and I would then create a new Samsung account altogether if the user wants to even go that far (I mean, I would want that, to get theme store, Samsung apps, etc.). But if this theory is right, and it is tied to this security service, the "cache and data" needs to be factory reset on the Samsung end and the way to do it is described in this paragraph.
So those are my thoughts. I just factory reset the Note for the last time and its being sold. Perhaps my theory is the fix. Billykac I wish you luck if you want to try out my theory. At least this is something new not mentioned before. It feels right too as the cause.
Adam
If you perform a factory reset and allow the phone to settle in for a few days, you will get a pop-up
, Attached are a few screen shots