If a podcast feed is functioning normally but episodes are missing from iTunes consider the following:
If iTunes displays all new episodes but is missing older episodes, your feed may be running into a size limit.
FeedBlitz can handle feeds up to 1MB in size, for both input and output. If a feed exceeds 1MB in size, FeedBlitz will intelligently truncate the feed by dropping the oldest episodes from the feed. The size of your feed can be checked by clicking on "Diagnostics" at the bottom of the Quick Info tile within the feed's dashboard.
The size of your feed is determined by the number of bytes within the source xml file. The media (audio or video) does not contribute to the size of your feed as it is a link from the feed and is not stored within the feed itself.
If the output of your feed is missing older episodes, it may be exceeding the 1MB output limit. You can reduce the size by eliminating some of the inclusions that FeedBlitz bundles into your feed such as Related Posts, Recent Posts, and Recent Comments. To change the inclusions click Settings from your feed's dashboard.
If no episodes or only some episodes are displaying in iTunes, check your feed to ensure that the media enclosures are being included; without the media file, iTunes will not display the episode. Look at your FeedBlitz feed and make sure that the media icon(s) is(are) displaying within the posts. If not, take a look at the settings within your site and make sure the links are properly configured within your post.