DBJ said: View Post
Well thank you for your clarification of my clarification but I think it was not necessary :)
This issue is now muddled over here and we/you should open a new thread with clear diagram for explanation.

of course other good people have noticed this issue too ...

And what about MSFT? This is yet another case of over engineering of otherwise clear solution (use user UID). To a self inflicted problem.
In any case this is not how modern OS should be coded. This is a BUG. And the clear indication of lack of UAT.
It should be properly setting the permissions on new files. The problem that they are reporting is that their UID is the first 5 characters of their email. They should give you the option to choose the name of your user folder, but setting the UID to the first 5 characters of the email is no bug. It's just a weird decision.