Hybrid sterility can make plants more attractive to pollinators, some flowers once fertilized stop producing nectar and some hybrids avoid this. Other times hybrids may have a mixed morphology that doesn't fit pollinators as well. It really depends so you are right to be suspicious (prime example of a highly attractive sterile plant is Salvia x Amistad) .
I only grow local forms of the native yarrow, Achillea borealis (everything else dies lol) so I can't speak on your plant. However, even my native yarrow is not attractive to butterflies. The small flowers are pollinated by smaller bees, hoverflies, and pollinating beetles but not butterflies in my experience.
