The cause is a bit different, but fixed for the next update in any case.
Thanks for looking into it.
The client on my side just updated and I think it has broken something about the Vanishing Powder 'nade... I am trying it out in Core City with two Praetorian guys. It never puts me into stealth now.
The issue that I was trying to point out before was that when no enemies had you in sight, but you're still in combat, the 'nade wouldn't put you into stealth. I was trying it out in that Protectorate port at Core City - the one with the snipers, turrets, cruiser and so on. When I shot an enemy down, but there was another relatively close to me(in his sight), the 'nade would work. But when all the enemies close to me were dead the 'nade would no longer put my char into stealth, basically leaving me open for snipers.