Visibility of smart symbols depends on layers

If the layer of an instance of a smart symbol is hidden, all the geometric elements of the relevant smart symbol are hidden, too. If the layer of an instance of a smart symbol is visible, the visibility depends on the settings you have made for the layers of the individual geometric elements.

Important: if the layers of the geometric elements of a smart symbol are frozen whereas the layer of the instance of this smart symbol is modifiable, the smart symbol can still be edited (e.g. deleted or moved) as a single entity.

See Example.