Re: Infiltrator - Artillery flare gun bug
That bug happens if you fire the flare into the ground too close to you. To bypass it, I recommend the approach that actually was the one intended by devs - aim flare gun in the air and fire. A map with white dot will open. That dot is your flare. Click LMB again when the dot is over the place you want to attack - that's where artillery strike will go. The practical range is up to 220-230m.
Example of the shot type I mentioned: https://www.youtube.com/watch?v=x5wAJDpJVYI