Toggling variable on sub anim instance node clears its original value

If the user enables Expose for a variable on a sub anim instance node, the original value of that variable is lost.

1. Open QAGame in editor.
2. Open the animation blueprint QAPawn_AnimBP.
3. Set the value of the Speed variable to 200.
4. Compile.
5. Close the anim blueprint.
6. Open the anim blueprint SubInst_Crash.
7. Set the Alpha on the Blend node to 1 and compile. Note the Speed value carries over (the mesh walks in the viewport).
8. In the Details panel, enable Expose for Speed.
9. Compile again.

RESULT:

The original value is lost.