My fridge is a real POS, sometimes it freezes beverages solid. It has real poor temperature control. Well, this happened to $50 worth of RTD berry flavor Huel. Froze all of the bottles into blocks of ice. Well, I thought it would be no big deal to simply let them thaw out back into liquid. WRONG! It does thaw out but back into a gritty, oatmeal consistency. Completely undrinkable. No amount of shaking would restore it back to it’s liquid form.
Try blending them. Nut milks consistency changes when frozen but if you put it in a blender once thawed you can get back it’s original consistency. You might get the same result with your RTD.