Does the engine ever just "mess up" with no pattern or decernable reason?

I have a beam particle effect that looks like a laser coming out of a first person gun that i give new start and end points, turn visible, then set a timer to turn invisible. Sometimes the particle effect plays and sometimes it does not. To test it, I load a level, fire the gun, and see if the beam show up. I do this over and over and it sometimes works and sometimes doesn’t and there is no pattern as to when it works whatsoever. Is there some possible rounding error or something that’s abstracted away from me that I have to work around?

generally things have a reason as to why they dont work, usually its user error except when theres a bug or your install is corrupted. but most times the issue is in how something is implemented by the you the developer (in this case i mean all of us that use the engine).

share how you implemented your system and we can see if we can help from there. thorough explanations and pictures are always a big help.

Yeah, me messing up is more likely than the whole team at epic messing up, but I thought there might some common beginner’s mistake that causes such unpredictability. Integer division was the “gotcha” when I was first learning Java, but in that case it was a predictable outcome every time.

So basically, my gun can fire unscopped fully automatic, or scoped semi automatic. Both options are functions that get called and do the same thing but with their own particle emitters. They make a line trace where the player is aiming, takes the begin and end of the trace, gives it to a particle system which becomes visible for about .1 second and then becomes invisible again. Here’s some pictures:

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Never mind, It’s fixed now. I still don’t know why it wasn’t working, but I changed to spawning a new particle emitter for each bullet trail and deleting it once its done and this seems to work.