3D models from Google Blocks

Hey guys, I apologise if this is a stupid question but I am a total newb to 3D modelling. I’ve been toying around with Google Blocks which is a VR 3D modelling tool and I’ve created my first ever 3D model. I’m not sure if this is the right way to do it but my model is essentially a composition of lots of different 3D primitives. When I import this into blender it seems to load just fine, but when I attempt to import it into an Unreal project it seems to add each individual primitive as its own mesh.

So my question is this: am I approaching this all wrong? Should each model be carved from a single primitive? Or is there a step I am missing? All the tutorials I’ve seen import the fbx files straight in and they are loaded as a single mesh without any extra steps.

I’ve attached screenshots of what gets loaded into Unreal when I attempt to import the FBX or OBJ files, and another screenshot of what the model looks like normally.

Kind regards, Aaron.