Recently Amarok trashed its podcastepisodes database. I repaired it using "$ myisamchk -r podcastepisodes.MYI" but were many references (typically about 6) to each episode. I unsubscribed to all my podcast channels and resubscribed to them. Now the opposite problem. The channel URLs show many episodes, but Amarok shows only a few.

A typical example: "http://feeds.wnyc.org/onthemedia" shows a large number of episodes, but Amarok shows only one: "Apocalypse, Now", the latest one. Is something broken (Amarok or the feed), or am I missing something?

Amarok Version 2.8.90
KDE 4.14.32
Fedora-26 Linux, all updates installed.

Have a look at the subscription details of the podcast, you can choose how many episodes you want, the default is the most recent episode for many. This can vary depending on the remote podcast settings.