TL-50 secondary weapon fire

This visual glitch also occurs online, not only in single player. It happens pretty frequently, around 40-60% of the time. Description of this thread may not be enough to track this bug down, so here is what I found.

Steps to reproduce

1) Join Blast (Doesn't matter which map)

2) Choose Heavy with 1th and 3th mod on the weapon (third one is the secondary fire, other one is additional)

3) When you are spawned, try to shoot your secondary fire by zooming with the gun. Then you may see your blue projectile, if you see it (works properly) then respawn and start with step 2.

Observations

1) It happens frequently, around 40-60% of the time

2) It at least happens in Blast.

3) The projectile is invisible (no blue animation), but the actual bullet will shoot, causing damage at the enemies. You will receive damage points and the secondary fire goes into cooldown. This works all as intended.

4) When the glitch occurs, you won't be able to fix it without respawning. You have to die to have another chance that in the next heavy life you will be able to see the bug. There is no other way to get the secondary fire visible again. This doesn't work as intended.

5) The sound of loading up the secondary fire works as intended, the sound of shooting the secondary fire is not, you cannot hear it firing or hitting anything, only if you damage enemies or you get a kill.

I have a video, but I don't think it is worth uploading, it is just that the blue projectile is not visible, nothing more.