Episode MP3s Not Showing Up

[Ryan Luke Winslade]

My episodes are all listed in my feed - feeds.feedburner.com/PastorsMiddleKid - but only a few episodes have the "Play Now" button, indicating that there is an MP3 attached to the embedded file. The problem is, I have gone through exactly the same process with each of the episodes on Wordpress, and only a few actually show up. All of the episodes' embedded players work on Wordpress, showing that the files embedded from Archive.org are legitimate links, so the problem seems to be with Feedburner. I have searched for the answer for a number of days and have found no solution. There seems to be no reason whatsoever for episodes not showing up.