Pose is not updating when additive is applied

When the user applies an additive base pose to a pose asset, the mesh does not update in viewport.

This issue occurs in 4.15 and 4.16.

1. Open QAGame in editor.
2. Open the pose asset Test_Pose.
3. In the Asset Details, enable Additive.
4. Set Base Pose to Smile.
5. Click Apply New Base Pose.

RESULT

In the viewport, the mesh does not update correctly.

EXPECTED

The arms to be stretched to the side and the face to make a smile.