Cause

When expanding a placeholder object the earlier object references were accidentally deleted. This means the placeholder object has variables and value sets, but no object reference in the table of the Assignment tab.

Solution

To expand placeholder objects, proceed as follows:

1. Press and hold the [Ctrl] key.
2. Then click all the objects that you want to add to the placeholder object one after the other in the schematic.
3. Then release the [Ctrl] key and click the right mouse button quickly on the placeholder object.
4. From the popup menu, select the menu item Assign objects to placeholder object and double-click the placeholder object.
   
   In the Assignment tab of the Placeholder object dialog, the properties of all selected objects are shown in the table.
5. Assign a variable with a suitable value to the desired object property.
6. If required, start a new check run.