Cannot add illuminance map or interior partitions

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Anytime I try to add an illuminance map or interior partitions to my model, I receive the message "You need to be in a Space to add an Illuminance map."

I have tried creating a space both with the "Create Spaces from Diagram" tool and with the standard "New Space" tool. I then make a section cut, and attempt to place the interior elements.

In the Inspector, the object does register as a space...

Anyone know what I'm doing wrong? Thanks!!