Pretty sure I saw it mentioned in the main bug thread too but the problem seems to be with the speed of projectiles. The activation on steal is instantaneous, while projectiles move more slowly. Which means you fire a shot with a ranged weapon, steal (giving you stealth) and that gets immediately broken by the projectile you fired before stealing. I have the same problem using blinding powder with ranged weapons. The stealth from powder activates instantly and then is broken almost straight away by my then in-flight projectile.
Its quite annoying because it means I have to stop attacking for a second or so to make sure my skills wont be wasted, which makes blinding powder far less effective as an escape skill.