Anim Notify State - Particle System not triggering all the time

I have created an anim notify state blueprint and overridden the ‘PSTemplate’ function to set a custom particle system based off the players equipped weapon.

This works in some cases however sometimes the effect does not spawn. This isn’t an issue for specific animations. It will sometimes work for a given animation and then it won’t the next time.

Can anyone think of a reason why this would happen?