Well having trawled through every relevant post i could lay my mouse on it would appear other people have similar problems but none quite match my scenario.
- I've cloned the listbox and removed it from the container which in turn unlinks it from the other related objects.
- I've changed the field behind the cloned listbox to the specific object (rather than the dynamics of the previous expression/variable approach which as nice as it is i don't think containers/listboxes are ready for it yet) on that dashboard sheet.
- I've hidden the object behind another one on the same sheet.
- I've added a button to the sheet that will export the hidden listbox to excel. It's a fairly simple listbox and a one line macro (Call ActiveDocument.GetSheetObject("MyListBoxName").SendToExcel()) so no big performance hit.
Would have been nice if the original approach worked and presumably as newer versions come out that sort of thing will!? But all is working nicely now.