Did you ever try the registry change by ToddStarlin? This has been fixing it on every new laptop I purchase for my company. It is a lot faster than reinstalling Windows. By clean install, do you mean a different version of Windows from CD or a Flash
drive? If you mean factory reset, I could see the problem still occurring. As soon as Windows opens for the first time, the App store starts trying to do a bunch of updates on all the Apps including the pre-installed App version of Microsoft Office that comes
with Windows 10. If you go in the store and find your way to updates you will see them all downloading like crazy without asking you.
The registry fix removes the folder that causes Office to think it is a Microsoft Store App and not a standalone version that is installed. Removing the folder from the registry has been fixing this issue for many users on different forums. This is
faster and possibly less dangerous than messing with changing .net when it probably didn't need it. This is of course my opinion, but I set up laptops multiple times a week and this has been a ridiculous problem until I found the registry fix.
I have only ever had to remove this one folder and it always works.
H****KLM\Software\Microsoft\AppModel