Behavior in editor (working as desired): Undesired and inconsistent
behavior in build: The player can move grabbed parts on their local
z-axis using the touchpad. The behavior works as expected, and
consistently, in the editor. But the behavior break...
Edit: Just tested the feature in Unity 2018.2.15f1 and the behavior was
consistent between editor and build. Not sure what caused the issue in
Unity 2017, but I can call this 'solved' for now.