Both hay and pellets are more “hardy” in terms of texture and effort needed to chew them down. Because of this, I wonder if they are having dental issues, preventing them from eating the hay and pellets. Selective eating is a common sign of dental discomfort.
It is interesting that both your rabbits are experiencing this (could just be coincidental), but that makes me wonder if there were any recent changes to your hay and/or pellet supply? Perhaps they’re a new brand, recently exposed to something that would change their scent/taste, etc.?
It is extremely important that your rabbits eat pellets and hay, especially for the fiber, teeth grinding, and needed minerals/vitamins provided from them. I recommend a vet visit to have their teeth examined for molar spurs.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.