Teamcenter Visualization TcVis 11.6: Assembly 3 not appearing on left-hand side of screen as expected

I have a 3D model open in TcVis and I can no longer see the window where the assembly tree is located or that smaller window that has a red rectangle around it so I can quickly zoom in on a model. How do I restore that?

To restore the Assembly Tree and Navigator windows please go to Menu > View > Docking Windows > check on Project Workspace and Navigator:

You can also choose to dock them or "snap" them into place or have them "float" on the screen: