For actions that are triggered on the Input mapping context, simply adding or removing an InputMappingContext with no related key override with the bIgnoreAllPressedKeysUntilRelease option will cause the event trigger to stop.
This happens because the trigger array is deep copied and therefore fails to compare with the old mapping.
Sorry this issue was already fixed in 5.3.
# Create a project with ThirdPersonTemplate Or ~
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-192648 in the post.