@Yna_Db @Einar_Raknes @Ewan_Opie I think you need to ungroup and regroup your group as shown by @Martin_Spence1. Revit doesn’t like if you copy group multiple times for some reason 
. I think this happens when you copy group or else it works as expected. I tried creating multiple groups with one instances and it works fine. Below is the process in action.
