This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.
A warning is needed before allowing users to uncheck update Navigation Automatically. A user has done so and then created a nav mesh that was 1,000,000 by 1,000,000 in size and they can no longer open their project due to the initial load.
Expected: A warning would be given either when scaling the nav mesh or when unchecking the update automatically option
Result: the project hangs when trying to save or potentially when trying to open
Head over to the existing Questions & Answers thread and let us know what's up.