I have been using the Grav-gun recently and have noticed an issue with the skill Gravity Implosion. If I click directly on an enemy with the skill there is a chance that it doesn't last for the full duration (5 secs), ending early. This seems to happen when the enemy that was targeted dies quickly. It does not happen if the skill is targeted at the ground instead of directly at an enemy.
I am not able to 100% of the time reproduce this, but that might be due to me not targeting a weak enemy consistently.