The latest episode in the Store is #89 of June 11th. Since then three have been added, and these all appear when subscribing. The latest episode was posted only yesterday, so it's quite normal for it not to have appeared yet, but the previous two should have.
There's no apparent reason why this should be the case. I can't see any problems with the feed, which as I say works in iTunes and validates in FeedValidator (with only a couple of minor points which don't matter).
I did have some difficulty accessing your episode files. Though I could play and download episodes in iTunes (though the server was a bit slow to respond) I can't access an episode file in Safari as I should be able to - on one try it simply didn't load, then on another I got 'the server is not responding'. You should look into this. That in itself shouldn't cause the episodes not to appear in the Store, just possibly show difficulties if you try to play them.
It's not unknown for the Store to 'stick' and fail to update a particular podcast for a longer than normal period, and this may be what has happened here. It usually sorts itself out in the end, though it's pretty frustrating while it's doing it.
Give it another couple of days and see whether it reacts to the latest episode. If it and the other two don't appear you could try Support, though you may not find them wonderfully helpful. Go to https://itunespodcasts.zendesk.com/hc/en-us/requests/new and click the disclosure triangle at the right of the 'Choose a topic' field - I should choose 'Other' and proceed from there.
