Thanks! I bred it with another Ralts, and it did the trick. I hatched one more egg with the Ditto, just to see if I'd get lucky.When breeding anything with a Ditto, the Everstone must always go on the Ditto for the Everstone trick to work. To solve your problem, you could either get a Modest Ditto and give it the Everstone, or breed any male Pokémon in the Indeterminate egg group with your Modest Ralts, keeping the Everstone on the Ralts.
Got another Timid one. So weird.