After selecting 3D Layout Design > Insert Cable/Bus Object, folders appear in the Part Tree pane but no part numbers are found or some are missing, even when the "All Parts" folder is selected in the Part Tree.
For part numbers to be available on the Insert Cable/Bus dialog, they must meet the filter settings. Either the part numbers or the filter settings need to be adjusted.
The Part_Type value must be VAR for a part number to appear on Insert Cable/Bus dialog. Parts Database Manager can be used to modify the Part_Type value.
Select the User Settings tab.
Find the "Cable/Bus Filter" node and note the values for FilterField and FilterWord. Only part numbers with the value specified in FilterWord contained in the field (column) specified in FilterField will appear on Insert Cable/Bus. The default FilterField is Discipline and FilterWord is Cable, meaning that part numbers with "Cable", "cable", "Power Cable", etc. in the Discipline column in the parts database will appear on Insert Cable/Bus.
Add the appropriate values ("Cable") to the appropriate field ("Discipline") for each cable part number using Parts Database Manager, and/or specify the desired values for FilterField and FilterWord on 3D Substation Layout.
Quick Filtering in the Parts Database Manager
Part_Type filter values
Select Manage > Admin Management > 3D Layout Settings to open the 3D Substation Layout dialog