Thank you. This was my issue as well. I had “Do Collision Test” set to true. This option, according to the tooltip, is used to prevent the camera from clipping into the level. The spring arm appeared correct in the Blueprint Viewport tab and it worked fine when its actor was in a different level with a sky sphere in it, but it stopped working after I placed it in a new completely empty level (the arm length appeared to be locked to the bounds of the static mesh in my actor and could not be made to extend farther than that even though in the Blueprint Viewport it was shown correctly).
I’m guessing that the engine uses geometry in a level to determine its extents and since a completely empty level has no geometry in it (aside from a mesh in the actor itself), the spring arm will lock its arm length to the extents of the mesh on the actor.
This wasn’t very intuitive as one would imagine an empty level as having no extents and thus no limit or bounds to restrict a spring arm to, but I suppose this was done for performance or some other underlying architectural/technical reason that I’m not privy to.
Either way, Thank you again zmcdn for this tip and I hope my findings help someone else as well.