I think that is the normal situation. I ordered a subscription two years ago, got two or three issues. When I got the first issue, I was impressed, so much so, that I emailed and asked to purchase all back issues. Tried a couple of times more. Never got a response!
Since this was an email sub, the cost of the back issues to 37th Frame was Zilch.
When subsequently checking on my late subscription, I never did hear from him. I don't know if I'll ever see another issue. I see him on a number of sites including his own blog. I don't think he's a bad guy out to get money from unsuspecting folks but a lousy businessman.
I just assume the issue will show up when he gets around to it, interesting material he does write.