Credit for the solution in this post largely goes to this comment on the Apple StackExchange site. I do a few things differently, especially for the last step.
The same awfulness can be seen in the Podcasts app on iOS.
When a split like this happens in an album in Music, the problem is often solved by group-editing the files and making sure they have the same
Sort Album, and
Sort Album Artist. In my experience 99% of splits are fixed if you make sure those three are exactly the same.
That doesn’t fix the podcast split, however. I think I detected the problem often around the same time a podcast provider (especially noticeable with a whole network, like 5by5) changed feeds, and my guess was that iTunes (and the Podcasts app on iOS) treated the new episodes with a different feed as a different podcast.1 When looking online for a fix, I found this comment which confirmed my earlier guess - the key is the feed URL.
I used ID3 Editor, which you can try for free, and costs $15 (which I think it has earned) for a single user license. First you need to get the right (i.e., most recent) feed URL. Go to iTunes and drag the most recent episode to ID3 Editor’s icon.
In the window that opens, you’ll find the podcast’s feed URL in the Podcast tab:
Close the window, and press
Shift + Command + O to open a group of files,
navigate to the folder with the rest of the podcast files, select them all, and change their feed value to the proper one you copied.
Once you update those files, the tags on those files are changed on disk, but iTunes isn’t always watching. You have to do something to provoke it to check the file on disk and update the tags in the library.
To update iTunes’ library, you can go the long route and play each updated file. When it starts playing them, iTunes will look up the files on disk and update its tags to what the file actually has. You only need to play a second or two of each podcast, but that can still take ages.
Select all the episodes you want to ‘reload’ or refresh, and click the Refresh item in the scripts menu. Done. You may need to select Music or some other iTunes category before you can come back and see the changes take effect. Relaunching iTunes would have a similar effect.
It can be tedious to apply this fix to all of the podcasts that suffer from this problem. The longer you’ve been listening to podcasts, the more of them are likely to be broken in this way. But it’s extremely worth it. Seeing three separate but identical album arts for a podcast on Podcasts for iOS and not knowing which one contains the episode you want is just lame.
P.S. I know there are people who hate the window shadows in the screenshots and want them disabled. I don’t care. I like them.
With all due respect to those inside Apple who have worked on this, but this seems stupid. Why not make the grouping rely on
Album, and ignore the URL if it changes? URLs are much more likely to change than the name of the podcast or the tagged artist. ↩
I got this script ages ago, and unfortunately I don’t remember from where or whom to credit for it. ↩