Thank you, Shawn: I sincerely appreciate that!
A couple hours ago, as I was trying things following my latest comment here, I removed the Blubrry Podcast Directory from the PowerPress settings > Destinations tab > Podcast Directories, and re-added the podcast to the (at this point only) post on the site. No change showed up at the podcast listing at Blubrry (I don't know how soon that normally happens), but I was able to get it to play on Podcast Addict.
Returning now to the Directory Listing (
https://www.blubrry.com/blackwater/), I see that a 2nd instance of the episode has appeared, and is correct in all particulars. The RSS feed (
http://lordblackwater.com/index.php/feed/podcast/) has only 1 <item>, which is correct really, so the extra nonfunctional one is a minor problem at worst.
Will removing the Blubrry Podcast Directory kill my ability to get stats through Blubrry? I'd hate to lose it, but again, it's less a problem than my URL oddness.
It looks like the next thing to do is return the various parts to functionality, checking that nothing crashes into Blubrry functionality.