Well it's pretty easy to just save a prop out as a new .OBJ and then import it again.  There's no CR2 file to deal with for a prop.  I would want to know exactly how to find the references to the geometry file in the CR2 file so I could change it and point it to the new one.  That's how it works isn't it?

You are SO right when it comes to tenacity, especially with Poser.  Of the myriad bugs I've encountered, I've always eventually found a fix, work-around, or answer.  Some took me a couple of years, but eventually I found a way.  These transparency problems are the latest.  Oh, and sometimes, after using Poser for a long period of time, a prop (usually a hair prop) suddenly becomes separated from the figure's head and will not re-attach for all the money in the world.  Probably a memory problem.  In that case, I just save the scene (or all the poses, etc.) and restart the program.  But it's bizarre.