If an Actor that initiated a dynamic force feedback is destroyed, the rumble will never stop.
Create an Actor Blueprint
Set up the event graph as shown in the attached screen shot
Place an instance of this Actor in to the world
Play in Viewport
Rumble will not ever stop
EXPECTED: Rumble will stop
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-44385 in the post.