Funky Rigify Bug discovered

Hey all,

I’m posting a strange rigify bug because I’m fascinated by it and I don’t have a definitive answer to it.
I have a simple scene that has two meshes and a lamp. One mesh has two materials assigned to it.

I create a rigify human meta-rig armature.
Without making a single adjustment I hit generate and this message appears:

seems it can’t find the hips.

What’s more is that two additional meta rigs appear, and an empty rig

I decide to delete everything from the hierarchy to see if it has something to do with an object in the scene. Same thing happens. If I create a new file, append the object or the scene and try this process again the rig generates just fine.
What is it about this file that makes a fresh meta rig not recognize its parts?