Hi Alexander
The visibility of content depends on whether tenant isolation is turned on and also whether the course is in a tenant category or a site category.
For limiting visibility in reporting
To limit the users included in the report to those in the user's tenant, scroll down to the Enforce user visibility restrictions section and enable the Show records based on user visibility rules setting.
To limit the content of the report, scroll down to the Enforce sitewide visibility restrictions section and enable the Show records based on audience, course and workspace visibility restrictions setting.
See Multitenancy reporting for more detail
regards