Try searching adjacent seeds since if you had 5 Pokemon in your party the step counter would advance it 5 frames not 3. It's possible a nearby seed has those IVs on frame 21.
My Pokécheck Pokémon
<~Nexus> Mat's seen things that would make you wake up screaming in the middle of the night NO MORE RNG NO MORE RNG
<CDXCIV> kittens is not a Pokemon.