Here's the gist of my issue:
The iTunes Store currently shows only 4 of my 8 total episodes:
Likewise, my RSS reader shows only 4 episodes (the same 4 that the iTunes Store shows).
And the subscribed podcast in my iTunes Library also shows all 8 episodes.
So... why are episodes 0, 1, 2, and 7 missing from the iTunes Store and from my RSS reader subscription?
It seems as if the issue lies with Feedburner, not with iTunes, my RSS reader, or my blog (hosted by Blogger).
I've tried pinging Feedburner, and I also resynched the feed on Feedburner. So far, nothing has fixed the issue.