Why Copilot Studio Agents Can’t Return SharePoint Results for Guest Users in SSO-Enabled Apps

In SSO-enabled environments, Copilot Studio agents can query SharePoint using the signed-in user's identity but this breaks down for guest users. Even if they have access to both the agent and the SharePoint files, the agent returns no results. This blog explores why delegated permissions, Graph Search limitations, and tenant-bound licensing prevent guest users from retrieving content through Copilot Studio.