Inactive Users by Service report in Nova shows no data, but the Usage reports in the Microsoft 365 Admin Center has data there.
The following possible issues have also been checked:
Where to find the reports:
Nova > Usage & Adoption > Inactive Users by Service
M365 Admin Center > Reports > Usage > (Active users - Microsoft 365 Services) View More > Services.
If all of the troubleshooting steps listed above have been attempted, but there is still no data appearing in Nova, then Anonymization / Obfuscation of user data must be turned off.
More details about this can be found in the article linked here.
The customer must log into the Microsoft 365 Admin Center.
Navigate to Settings > Org settings > Reports
Uncheck the box for "In all reports, display de-identified names for users, groups, and sites."
Allow time for new scans to run.
After the scan is completed, data should appear in the Inactive Users by Service report.