When forcing the app to the background the force feedback will continue on some android devices. This was reproduced on the samsung nexus 5 by clicking the home button while running force feedback in the app.
Result: The device will continue to vibrate from the force feedback
Expected: The Force Feedback would pause while the app is not focused by the device
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-66592 in the post.