When the user minimizes or backgrounds an AR application, and re-opens it, new AR sessions will fail to start
Observed Result
Camera feed fails to display, with subsequent attempts to start resulting in the message "Failed to Start AR"
Expected Result
User is able to start and stop AR successfully after minimizing or suspending an AR application
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-116035 in the post.