Hello @restartneil,
Thanks for being a PowerPress user!
Officially, Apple no longer supports itpc://. Apple has asked us to support the subscribe links to itunes, example: https://itunes.apple.com/us/podcast/blubrry-powerpress-community/id430248099
Only the iTunes desktop application will handle itpc:// feed URLs. More importantly, itpc:// feed URLs can only be non secure, the itpc:// does not work if your podcast feed is on a secure site, or https://. The iOS podcast app has never supported itcp:// URLs.
The good news, if you still want to provide an itcp:// URL (if your podcast is not listed on iTunes), you still can do it by simply putting that feed URL in the iTunes Subscribe URL field in PowerPress settings, just replace http:// with itcp://. This is unofficially supported, we were asked by Apple staff to no longer support itcp:// directly but they never said anything about us not preventing you from entering such information in your own settings.
Thanks,
Angelo
Thanks for your help, Angelo.