Anyone participating in competitive sports at the college level or beyond needs to realize that media attention is fickle. Your rewards for winning an event at NCAAs are crossing the line first, being able to (honestly) say you were the champion, and scoring points for your team. That's what you can count on. How much attention you get is a crap shoot, only partially correlated with performance. Ask any 100m hurdles woman not named Lolo Jones, to pick just one example of many.
But the OP has a good question as to, okay, why so little attention given to Mackie. I don't pretend to know the whole answer - and again, some of this is just chance - but I think part of it is the story element. Hasay is a useful comparison here. A lot of people know Hasay's story, because she got a lot of attention in high school based on making it to Trials. So it's been interesting to watch how she's fared on the college level. She didn't flame out like some HS stars, but neither has she shown real domination. So it's not clear if she's going to keep progressing (ala Rupp) to be a top pro at some point - and if so, at what distance - or end up as someone who can "only" place high at NCAAs. So with each season, many of us are interested to get an update on her story, which we've been following for some years, and see how those questions play out. Fernandez would be a similar example (albeit with different particulars).
We don't know Mackie's story yet, at least most of us don't. That's no fault of hers, no negative reflection on her. But when I saw the results with her name, I didn't have any narrative to connect her with, the way I do with Hasay or Fernandez or others. Over time, if I hear more about her and she keeps running well, then maybe there will be a "Nachelle Mackie" story. Just like I don't recall many people nationally paying too much attention to David Torrence in college, but he started making a name for himself then and followed it up by doing some things as a pro, so now there's kind of a DT story (for good or ill) that many of us follow.
Having written this, and sorry for it being longer than intended, it strikes me that not having much of a "story" out there about you could be a good thing. In other words, I'm not sure Mackie is really missing out on anything by not getting the kind of attention that Hasay (and others) do.