You try to expand a group in your Permissions matrix report and get the following error message:

The group '{0}' uses a custom SSO provider that ShareGate Migrate does not support.

Your Active Directory (AD) is likely synced to a custom identity provider.

Because the information is not directly available in your AD, ShareGate desktop is unable to fetch the information of your groups.

This includes the user information necessary to expand your groups in the Permissions Matrix Report.