AI Studio redirects to /520 and fails to list imported projects with “permission denied”

Google AI Studio
1
  1. Project: JARVIS MK1
  2. Project ID: jarvis-mk1-505320
  3. Your account is Owner (roles/owner)
  4. gcloud projects list successfully lists the project.
  5. gcloud projects describe jarvis-mk1-505320 succeeds.
  6. Generative Language API is enabled.
  7. AI Studio says “Failed to list imported projects: permission denied.”
  8. The Import Projects dialog becomes stuck/loading.
  9. AI Studio goes through 404 → /520.
  10. It happens in normal Edge.
  11. It happens in InPrivate.
  12. It happens on your phone.
  13. It happens using your phone’s cellular hotspot.
  14. A different Google account also reaches /520.