Thanks, Paloth.  It looks like this bug is new with version 301 and will more easily occur when a mesh is imported (apparently an empty mesh item/layer is automatically created when you do that).  So users of other versions or those who've built their geometries within Modo wouldn't encounter the problem, apparently.

I'm glad to have a solution, however!  Thanks, everyone!  :D

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.