My last episode is showing. My second to last... does not

There seems to be an ongoing problem with the Store which causes this sort of thing - a number of people have complained about it. There is nothing you can do about it yourself since your feed appears to be OK - it works when subscribing in iTunes. You should contact Support and request a re-index: this should sort out the current missing episode though you may get the same problem again later. Goto https://itunespartner.apple.com/en/podcasts/overview and click the 'Contact Us' link at the bottom of the page.