Why isn't my Podcast episode showing?

There is no evident reason for this - the feed appears to be OK and as you say the episode appears when subscribing. Probably this is simply yet another glitch at the Store end; there's a good chance it will sort itself out eventually.

I would doubt that approaching Support will make any difference, and I would advise caution as your episodes appear to consist of 'mixes' of commercially issued recordings, which if spotted by the Store staff will get you removed.

Matt,

I'm showing the WOD mix #20 is showing in iTunes.

-Fan

Yes: this is fairly typical. Some sort of glitch when it checks the feed, which then clears itself the next time it checks the feed, which it's evidently done in the last ten hours.