I have a solution for you, is easy but takes time.
first I just want you to know. these are all of the method ive tried.
reset Microsoft store
reset Gaming services
Run troubleshoot
SFC scan
delete OLE in regedit
added two (or delete) two folders located in Windows folder (folder name start with App, and cant remember the rest)
Delete device in Microsoft Account and added again
sign on/off Microsoft Account
reinstall MFS and digital ownership
restart pc like crazy
watched a tons of YouTube vids for solution
spend whole day just to search solution on internet
literally anything you can think of that I've tried
the easiest way is reinstall Windows and make sure you select delete all drive files (the one it says with less secure) or you can just erase C:\ driver. since all other drive is a backup drive. unless you install Microsoft app on it before, it will leave trace
Im downloading 91.36GB in game rn.
I hope this REINSTALL WINDOWS helps.
I've gotta say. If the method given by Microsoft aren't working it might be a bug they need to fix on their end. no offense. BECAUSE, ive contact support, and they have no idea how to fix it but giving you lot of method for you to try and troubleshoot them and still didn't work. which it will take way much longer them just do a reinstall of windows and have all other app setup rdy to go.
Think the easiest way
btw, be sure to **BACKUP ALL YOUR IMPORTANT FILES BEFORE REINSTALL WINDOWS**
also I don't think is a region problem, cuz I bought MFS when my region is set to Canada. I set to Taiwan (or any other countries) after reinstall windows and it still works.
I think might be something to do with Windows update or a "simple error" as computer name (device name) that is causing the problem but why? im not sure. as you can see theres a device section in Microsoft account, might be something to do with that. For example computer A is first registered in Microsoft account after reinstall windows it will registered as computer B which is a brand new PC, but seems you still own the Microsoft account, everything is bind to that account so you will be able to get everything back.
sry, too much talk here..anyways good luck :)