1. Here's how

In Lumion 8.0 to 8.5, Group Object Icons are always displayed in Move Mode - even if the Layer they are on is hidden:

1.1: You can hide the Group Object Icons by switching from Move Mode to Place Mode:

1.2: There are two ways to avoid selecting the Group Object Icons on hidden Layers:

• Select Place Mode and use the selection tools for Place Mode such as CTRL + Left mouse button on the Group Object Icons.
• Select Move Mode and use the selection tools such as the rectangle drag selection tool, but then remove any Group Object Icons in hidden layers using CTRL + Left mouse button on the unwanted Group Object Icons.