I’m still unsure of exactly what is going on but it seems that the only assets that won’t duplicate correctly is the Static Meshes that you added. If you look in the Scene Outliner they are duplicating but are loosing the referenced static mesh in the Details panel.
Your blueprints duplicate fine, as well as the blueprints and static meshes from the Starter Content.
I’ll continue to look into this and post back here when I have something. Make sure to post back too if you find anything.