You are sharing a web scene or web scene layer that contains a layer with symbols that contain 3D model marker symbol layers. These symbols are not displayed in real-world units. Scene Viewer only supports 3D model marker symbol layers in symbols that are displayed in real-world units.
Display the symbols in real-world units.
Hover over the analyzer message. Click the Options button that appears and click Change Layer Display. On the Layer Properties dialog box, on the Display tab, check the Display 3D symbols in real-world units box.
Learn more about displaying 3D layers in real-world units.