Attempting to scan whole environment by using the re-scan option.
Re-scan only scans exposed email and files, not the whole environment. Please See the Scanning scope O365 Securlet documentation
Typical exposure types are:
Internal: Files or mail shared with all users inside your organization, not just specific internal users.
External: Files or mail shared with one or more users outside your organization.
Public: Files or mail shared with any user who know the URL.
Unexposed: Files or mail not shared or only shared with specific internal users.
Rescan will not rescan the whole envionrment.
The scope of re-scan content is shown below:
Please see the 'Scanning scope' tech doc for additional information.