Particle system beam firing inconsistently?

I’m working on a VR project that uses a particle beam as a selection pointer.

For some reason, it isn’t firing off consistently. I’m turning its visibility on and off using an inputAction event pressed/released node. The problem seems to be getting it to fire off on initial level load (which it does about 50% of the time) - once it ‘gets going’, it seems to work fine. If it doesn’t fire initially, I can usually get it to show up but button mashing the input and swinging the controller around. Then it works!

Any idea what would be causing this inconsistency? Is there any possibility it could be failing is the ‘end point’ of my trace is a negative vector? (I get more consistent results if my initial fire is pointing in positive X space - but that could just be a fluke).

I’ve posted the relevant parts of my pawn BP.