Haptic Effects do not fire on Vive controllers

Playing haptic effects via the associated blueprint nodes (I.e. Play Haptic Effect, or Set Haptics by Value), does not trigger any feedback on the Vive's motion controllers. This does not reproduce using Oculus's touch controllers. Force Feedback Effects DO fire. Tested on both a Vive Pre and the previous iteration of controllers.

Found on //UE4/Release-4.11 CL-2895514

1. Hook up an HTC Vive with associated motion controllers
2. Open UE4Editor.exe QAGAME TM-MotionControllers -game
3. Press 'E' on attached keyboard (should log that the haptics testing has been enabled.)
4. Pull the trigger on either controller

Result: No haptics fired