I think the problem is that when you assign a group or component to a new layer, unfortunately the individual objects that make up that group, retain the original layer assignment, and so there is a conflict.
You can prove this as follows.
First make sure the entity control and the layer control are expanded and visible in the tray panel. Then create a new layer by clicking on the layer control plus symbol and make sure it is turned on (selected) in the layer list. Next select a group object on the original layer that you want to assign to the new layer, and in the entity control dropdown for this group item, change the layer parameter to the new layer name. Now in the tray layer control, turn off (deselect) the original layer, and you will find the group object stubbornly sticks to this original layer, and disappears from view. Now make the original layer visible again,and this time select the group object, right click on it then choose “Edit Group”. Now try selecting an individual object within the group, and notice how it has the name of the original layer, even though it sits in a group with the new layer name.This is where the conflict comes from.
A quick and easy fix is as follows. When you are in the edit group mode, right click and choose “Select” then “All connected”. Then in the entity control panel, from the layer dropdown select the new layer name. This will reassign all the internal objects to the new layer, thus matching the group layer name, and effectively remove the conflict.
Now when you turn off the original layer, and turn on the new layer, the group object appears.