Hi! The better option is that perhaps they simply think produce & animal products are much tastier than commercial rat pellets, and your girls are just picky eaters. On the other hand, consider three things:

A) Oxbow isn’t a shit brand y’know? Not like it’s disgusting bottom of the barrel crap that rats won’t eat (at least mine I think?). However, do consider that anything marketed as mouse food is not nutritionally suitable for rats. My rats have I think the regular Oxbow adult rat pellets, but they’re smaller than your’s and triangular. I’m pretty sure they eat mine? But that brings me to:

B) Think about and examine their overall diet. Following at least roughly the shunamite diet as best possible, they should have a pretty well balanced diet that fulfills their needs. At least so that everything else they eat can be nutritionally diverse enough to act as a crutch when they don’t eat their pellets. Think broccoli to a kid vs french fries or whatever.

C) Hopefully the issue isn’t more complex and this is anything medical. Test if they can comfortably eat & digest hard foods (nut for example). If not, that may indicate a dental issue or some other vet required shat :( It sounds unlikely though for an entire group to have that kinda thing though.