Multiple missile arts on a single unit

[Zanam]

Hello all. I've heard of a trick involving the Barrage ability that will allow a unit to have more than one missile art, but upon trying this out I seem to notice a major flaw.

Every time I get the barrage ability to stop hitting multiple targets (as all I want is the art effect), the glitch fixes itself and will no longer switch missile arts. As long as the multi-hit ability is going off, the multiple artwork part works. Does anyone know of a way to make the ability not add multiple targets, but keep the missile arts?