Geometry node not duplicating specific object

Hello all. I made the simple box skyscraper well enough with geometry nodes. Now I have a more complex object (an apartment layout) that the same node setup refuses to duplicate. I took out a child object (doorknob) and tried a few other things with no result. This new system has little useful documentation; does it break if an object has ngons or something?

Image preview | Dropbox file

The object you are instancing is just a simple box:

Maybe you need to apply this geo-node setup to a different base object and use apt unit instead?

Thanks for looking! That was the fix. It seems future projects without a separate ground floor object will need some kind of invisible object from which to start replicating.

not necessarily, you could ignore the initial geometry path here and just use whatever you generate with the nodes:

I mean, this also works:

But at that point, you could just delete the original geometry in edit mode