I tried to search some topic about my concern but I didn’t find anything. In a certain point of my design the Layer panel disappear without any apparently reason. What I have to do to have back this very useful panel?
There are various things you might mean by “Layer panel”. If you mean the layers window, get it from Window->Layers. If you mean the layers selection element that can appear in a toolbar, you can drag it there from the View->customize toolbar menu popup. If you mean something like jiminy-billy-bobs’s layers panel plugin, unless something is interfering with it you can get it back from View->Toolbars.
It’s possible, especially if you have a two-monitor setup, that the Layers dialog got moved off screen. If so, it’s still there, but just not accessible. Try resetting the workspace. Window > Preferences > Workspace > Reset Workspace.
I am using free SketchUp Make 17.2.2555 64-bit. Does the free version treat layers differently? Because I am missing Window > Layers option. I have Windows > Default Tray > Layers, but it looks different than Layers Properties that I see in YouTube videos and appears to be missing information when I try to follow written instructions. I’ve tried resetting workspace.
Except that it is a floating window not a tray and a few trivial cosmetic things, it looks the same on Mac. But even having Windows>Default Tray>Layers says you must be on Windows!