Microsoft Breaking Change: O365 Reports Return a GUID instead of the Userprincipalname (usually email)
Doing an implementation of SAM Pro recently and enabling the O365 Usage integration. (Microsoft Office365 Integration Profile).
Microsoft Announcement MC275344
Privacy changes to Microsoft 365 Usage Analytics
Microsoft has introduced a breaking change to reports that obfuscates the User Principal Name (userPrincipalName) to a GUID. Unfortunately this breaks the underlying Script Includes doing the pulls from Office365 to match up User Activity/Detail to the users in the sys_user table. Essentially you get a bunch of samp_sw_usage records with the users being empty.
Microsoft has a setting in the Office365 Admin center to disable this obfuscation (on by default).
https://docs.microsoft.com/en-us/answers/questions/420250/ms365-some-reports-showing-guid.html
Hope this helps anyone running into this.
https://www.servicenow.com/community/sam-articles/microsoft-breaking-change-o365-reports-return-a-guid-instead-of/ta-p/2318943