While running the Audit Report, an event is displayed with the "Events" column displaying an Unknown type.
Some events related to Office 365 apps are not yet supported by Sharegate.
If you see an Unknown event in the Audit Report, you can generate an audit report via Sharepoint. This report can be harder to read, but still holds useful informations.
To generate the Sharepoint audit report :
1. Go to your site collection's settings
2. Click on the "Audit log reports" link under Site Collection Administration
3. Click on the "Run a custom report" link under Custom Reports
4. Enter the same filter options you entered in Sharegate and click on OK
5. Open the excel file that has been generated.
6. Using the timestamp (Be careful, the date displayed in this excel file are in UTC), find the row corresponding to the Unknown event that you saw in Sharegate.
7. If this event does not seem related to Office 365 apps, feel free to contact us at firstname.lastname@example.org