Ongoing "corruption" problems with ExternalGroups via Graph API

Copilot Connectors use ExternalUsers and ExternalGroups to manage access controls for indexed items.

There are ongoing "corruption" issues with ExternalGroups.

By this, I mean something goes wrong on the Microsoft Graph side which causes it to behave as if an ExternalGroup doesn't exist in some situations, but not others.

We have created an ExternalItem restricted to a particular ExternalGroup, it shows up in the Index Browser, but later if we attempt to add a user to that ExternalGroup we may receive an error "404 The requested resource does not exist."

We understand there is some eventual consistency at play here, but sometimes these group issues never resolve themselves.

The report does not identify a repository file, test, SDK version, or reproducible entry point. Start by reducing the ExternalGroup and ExternalItem sequence to a reproducible Graph API case and compare the successful and 404 operations. Done means identifying whether the SDK contributes to the failure or documenting the external-service behavior with actionable reproduction details.