Hi Damian,
I believe this has something to do with your reference file, Turbine Locations.dgn. I noticed that you attached the 3D model to the Default model of the new.dgn. When this is done, it should automatically attach it to the Default-3D model of new.dgn as well. For some reason you either deleted it, or it did not attach itself. You will want to reattach the Turbine Locations.dgn to make sure that it creates the attachment in the Default-3D. I do not have your .itl, so it's a little hard for me to test to make sure this is the cause of it all. But after I did a few tests, I'm pretty sure this is it. If after you redesign your civil cell and it's not working, please let me know.
Holly
I believe this has something to do with your reference file, Turbine Locations.dgn. I noticed that you attached the 3D model to the Default model of the new.dgn. When this is done, it should automatically attach it to the Default-3D model of new.dgn as well. For some reason you either deleted it, or it did not attach itself. You will want to reattach the Turbine Locations.dgn to make sure that it creates the attachment in the Default-3D. I do not have your .itl, so it's a little hard for me to test to make sure this is the cause of it all. But after I did a few tests, I'm pretty sure this is it. If after you redesign your civil cell and it's not working, please let me know.
Holly