The reason it looks fine in the mesh previewer is because it’s reflecting a cubemap in the previewer. But when placed in the scene, it is using Lumen reflections which do not seem to support anisotropy. So you’ll only get anisotropy from the direct specular (lightsource reflection), and not from indirect specular reflections (reflections from the scene)
For now, I don’t know that there is any good way to overcome this, other than turning lumen reflections off, or switching to substrate materials
In the future, apparently Lumen is has added support for anisotropy: Lumen GI and Reflections feedback thread - #970 by jblackwell