Microsoft Defender Blank Screens on Mac

Blank or non-loading details pages usually indicate that Defender on macOS is not fully initialized because required system permissions or extensions are not correctly approved, even if they appear OK at first glance.

Check and fix in this order:

1. Confirm Defender is healthy

• Open Terminal on the Mac.
• Run:

    mdatp health
  

• If healthy : false or values such as real_time_protection_enabled : unavailable, real_time_protection_available : unavailable, full_disk_access_enabled : false, or issues like "no active event provider", "network event provider not running" appear, Defender is not fully operational and the portal UI can behave unexpectedly.

2. Verify system extensions are approved

• In Terminal, run:

    systemextensionsctl list
  

• Look for Microsoft Defender entries. If they show [activated waiting for user], they are installed but not approved.
• Open System Settings (or System Preferences) > Security & Privacy.
• On the General tab, look for a message that some system software was blocked and an Allow button. Approve the Microsoft Defender extensions.
• If prompted, approve both Microsoft Defender and Microsoft Defender Extension.

3. Grant Full Disk Access and privacy permissions

• Open System Settings (or System Preferences) > Security & Privacy > Privacy.
• Go to Full Disk Access.
• Ensure checkboxes are enabled for:
  • Microsoft Defender
  • Microsoft Defender Security Extension (or similar Defender extension entry)
• If not enabled, unlock with the padlock, enable them, then lock again.

4. Re-run health check

• After changing permissions, in Terminal run again:

    mdatp health
  

• Confirm healthy : true and full_disk_access_enabled : true. If health is still false, review the reported health_issues and fix any remaining permission or extension problems as above.

5. Reopen Defender and check alerts

• Quit Microsoft Defender completely, then reopen it.
• Sign in with the Microsoft account associated with the Microsoft 365 subscription.
• Try See details on the alerts again.

6. If issues persist

• From the Defender app on macOS, use Help > Send feedback to submit logs and details of the blank screens.
• Alternatively, sign into https://security.microsoft.com and review alerts from the Microsoft Defender portal; if alerts show correctly there, the problem is isolated to the Mac client UI and should be reported via feedback.

References:

• Installing Microsoft Defender
• Troubleshoot system extension issues in Microsoft Defender for Endpoint on macOS
• Get started with Microsoft Defender for Endpoint Plan 1