Candi,
I’ve found the same with some of my students. For the ones who really struggled, I planned lessons purely on rhythm and came up with some percussive vocal exercises helping them to learn beats and subdivisions.
It works wonders! Once they get rhythm, even to a basic level, they tend to understand phrasing a LOT better. Plus it means you can tell them what do do in musical terms if they get stuck, which I think is basically an essential skill.
If you want some of these exercises let me know and I’ll happily send them over 🙂