UEFN Platform Cook fails with invalid_results on custom map

Summary

UEFN platform cook fails repeatedly with invalid_results after updating a large, detailed Japanese house map. Map Check warnings (non-streaming actors referencing streaming actors) were fully resolved (0 errors, 0 warnings), and a corrupted orphaned uasset in ExternalActors was manually removed, but the cook still fails with the same error.

Please select what you are reporting on:

Creative

What Type of Bug are you experiencing?

Assets

Steps to Reproduce

  1. Open the project and start a session
  2. Platform cook fails with: “Failed to cook server/client request” + invalid_results
  3. Confirmed Map Check shows 0 errors/0 warnings
  4. Confirmed a corrupted orphaned uasset file in ExternalActors was found and removed
  5. Cook still fails with the same invalid_results error after removal

Expected Result

Session loads successfully after platform cook completes

Observed Result

Platform cook fails repeatedly with invalid_results, session cannot start

Platform(s)

windows

Additional Notes

Windows Fortnite build version 42.10. Project is a large, detailed custom map with many custom devices/props. Happy to provide the CookJobId or additional logs if needed.

FORT-1153810 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.