Hmm. That’s odd. My construct seems quite similar to yours.
<description>Arrested DevOps is the podcast that helps you achieve understanding, develop good practices, and operate your team and business for maximum DevOps awesomeness.</description>
<itunes:owner>
<itunes:name>Matt Stratton</itunes:name>
<itunes:email>matt.stratton@gmail.com</itunes:email>
</itunes:owner>
<itunes:image href="https://www.arresteddevops.com/img/ado-podcast-logo.png" />
<itunes:category text="Technology">
<itunes:category text="Software How-To" />
<itunes:category text="Tech News" />
</itunes:category>
{{ range (where .Site.Pages "Type" "episode") }}
<item>
<title>{{ title .Title }} - ADO{{ .Params.episode }}</title>
<itunes:author>Matt Stratton, Trevor Hess, and Bridget Kromhout</itunes:author>
<itunes:summary>{{ .Description }}</itunes:summary>
<description>{{ .Description }}</description>
<enclosure url="{{ .Params.podcast }}" length="{{ .Params.podcast_bytes}}" type="audio/mpeg" />
<guid>{{ .Params.podcast }}</guid>
<link>{{ .Permalink }}</link>
<pubDate>{{ .Date.Format "Mon, 02 Jan 2006 15:04:05 -0700" | safeHTML }} </pubDate>
<itunes:duration>{{ .Params.podcast_duration}}</itunes:duration>
But the output file DOES include 71 (which is all) of the episodes.
[Edit] Oh! I know why, because you’re using the built-in feed generator, which I don’t think you can override for size (which is why I ended up going to the template among other reasons)