Unable to use Volt Support with Molten Blast

Molten Blast is an attack with the Projectile tag; Volt Support states that it supports "Projectile Attack Skills that you use yourself", but cannot be used with Molten Blast. Meanwhile, Salvo Support similarly states that it supports "Attack Skills you use yourself which fire projectiles" and CAN be used with Molten Blast. Is this a wording issue in Volt's description, or is there something differentiating the two?