I've noticed on my gunslinger and my sniper Ballistic Dampeners (and the GS equivalent of Rapid Fire) disappear many times when I enter cover. Specifically cover behind an object not cover in place. I roll to the cover (or crouch and get slid into place if I'm too close for the animation) and the buffs appear for half a second and then disappear.
Has anyone else encountered this? They work normally when I cover in place but then I don't have the full benefits of cover. This doesn't happen every time I cover behind an object but I can't figure out how to prevent it. The only common thing seems to be if it's not absolutely level by the cover or something.