If you keep ammo in your sets (which i don't suggest) Is it perhaps a problem of your midshot changing range/ammo? It sounds that way.
This is the reason, and it happens to me as well. I use vanilla gearsets, but if you change ammo mid-shot, it will cancel the shooting entirely.
example
quickshot in animikii bullet
immediately range attack, which uses chrono bullet (and you don't equip your tp bullet
before your /ra macro begins pointing your gun)
result:
You will aim your weapon for a brief moment and then tuck it away, but the log will not explain why it did not fire off. The ammo swap prevented that particular action from being performed.
I guess realistically, you have to "load" your ammo before you shoot, not while you're shooting. makes sense why they never released any Snapshot+ ammunition, as that wouldn't work if you used it for preshot purposes