Makeshift fix is a wire mesh surround standing at least 4" off the feeder, so the Ibis can't just poke his/her beak in and hoover up the snacks.
Alternatively, find cheap food that you can leave on the ground for the Ibises, so they leave the feeders alone for the other birds.
Somehow, I'd thought Ibises were mostly meat eaters, slugs, snails, frogs and the like, so perhaps they would like hot dogs, suitably sliced.
Not sure the budget would allow that though.