Black meshes with projector

I'm working in Unity 2019.3.1f1 and am encountering the following visual error:

This is what the scene looks like normally:

As the projector's bounds sweep over a mesh, that mesh gets added to World Origin (0,0,0) and is completely black (edit: and also squished flat). I've toggled lighting and post-processing on and off and have used multiple materials (both transparent and non-transparent) who all have the same effect.

Is this a configuration problem or a bug?