I assume that the wiki just uses placeholders (these are very basic and don't hold any information besides the code; sometimes the DVD cover names contain additional information, I feel, e.g. some prefixes or postfixes besides the code), and the DMM site never had these on site,
If understand correctly, the OP references the publisher's site, and the titles in question are just not there. As if they never were. So, it seems that the question is more like, what made the studio to allot these codes but never use them. Or, more likely, what made them use these but never get the contents published — and not re-allot the codes. So, it comes down, again, to what happened at the studio, and, presumably, even before the release
Maybe to answer this kind of questions you really need to know how the JAV studios work, or at least how this studio works. From the marketing perspective, by the way, it seems detrimental. Imagine you're a collector and you want to collect all the Hunter titles, and you just can't. So, you call the studio (if you're hardcore), and, maybe, they explain it to you. Or make up an explanation...
The more you get into it, the more shady possible explanations become
Or maybe I am/we're just overthinking it, and they were like, "Screw it, nobody will care about three consecutive codes not being used". But that's how conspiracy theories are built: maybe these are coincidences, but they sure don't look like it. Moreover, just skipping codes like that... 日本人らしくない
To rephrase a certain comedian, Hunter could clear so much s...t up with a 5-minute press conference