The video below is showing how the five Visibility commands work in Project Manager.

• Hide - Hide selected elements
• Unhide - Unhide selected elements
• Isolate - Isolate selection
• Toggle Hidden - Show hidden elements
• Unhide All - Unhide all elements

The second video is showing which tabs are affected by the commands.

The ones that are affected are, inter alia, Model view, Summary, Element Ids & The tree view on the left where the elements are highlighted under the building, floor, and specific element type they belong to.