Have the original Playground working 
https://www.babylonjs-playground.com/#3EDS3A#249
Added q.normalize() on Line 518. Without it, it gave the bullet’s rotationQuaternion very high xyzw values, which caused initial xyz values of the Ray's direction to be massive (as shown in above image).
Not sure if this is a new bug (Ray attached to mesh with unnormalized rotationQuaternion via RayHelper initially has incorrect direction xyz values but then corrects itself in subsequent frames/physics time steps).
Very thankful the Playground is now working. Thank you so much for your help, @RaananW!