Thanks for asking.
Yes, I did solve the issue, sort of… by deleting those problematic feeds and replacing them with new ones (using custom hostnames) that reside on a different server. All the issues I was having with the category feeds, and how they were (not) updating in Apple Podcasts etc, have now been fixed.
I’ll keep using the WordPress site to promote podcasts, but I’m done with any attempt at category podcasting through PowerPress!
Thanks for your reply, Mike. I’m still having problems with both feeds on this account, plus other issues with episode descriptions in podcast players, so I may go back to hosting my feed somewhere else.