Update:
I took the whole thing down and started again. The reason I thought I couldn't catch any studs is because the portion of the wall that I tried to do FIRST doesn't have 16" center studs. I went crazy trying to figure out what was going on because my stud finder kept registering some crazy stuff. A little youtube taught me how to calibrate my electronic stud finder, but it still came up with a lot of HVAC and electrical hits that I am almost positive don't exist. I finally resorted to a single pre-drywall photo that happened to catch part of the wall in question in the background. That's how I figured out that in one area of the wall, they did two studs next to each other, then the rest of the length of the wall is just seemingly however they wanted to do it. 6 inches, then 17.5 inches.
So of the two sections, one I am confident with now that it has 4 of 7 holes catching studs.
The second (smaller) section has 4 holes and only the first one caught a stud.
The reason I lack confidence with the drywall anchors that Elfa supplies is because they are supposed to catch the back end of the anchor, and then at some point the screw should become difficult to turn. But that only happened on one of my anchors. All of the other anchors on both sections, the screw will just turn and turn and turn and never finish tightening. It looks fine to the eye, but get a screwdriver, and you can still turn that screw as if there is no resistance.
Finally, I decided to just go with it and put lighter items on the section that I am worried about. I also found two studs in that section that didn't line up with the holes in the track, and screwed some wood screws above and below the track. Trying to wedge that track up against the wall with the head of the screw. At least that will give me some warning if the thing does pull out of the wall.
Snow White -- The top horizontal track is a few feet below the ceiling. Do you screw it into a horizontal joist ? This was not even mentioned to me by Elfa.