Here is what Apple told me: “The <enclosure> tags for the episode numbers 209 to 221 within your feed are formatted incorrectly, which is preventing them from playing on the Podcasts App.
The <enclosure> tag has three attributes: URL, length, and type. In reviewing the <enclosure> tags in your feed, the length is set to (length=“0”) for the above episode numbers. The length attribute is the file size in bytes. You can find this information in the properties of your podcast file (on a Mac, choose File > Get Info and refer to the size field).
Please edit the length attribute in the <enclosure> tags for the episode numbers 209 to 221. Allow up to 24 hours for any feed updates to reflect in Apple Podcasts.”
Will someone tell me what I’m doing wrong and offer a fix?