I was playing Episode Three - Chapter 2 this morning, Catherine: Galileo, and towards the end, the jackal rangers and the elite went invisible, their weapons floating on the ground shooting me. It took me a couple of deaths to figure out that I just needed to aim at the weapons and to use grenades. Finally, when just a few were left, they came back.
Just thought I should report this.
If there is an official place to do this, point me in the right direction.