i need to know how this is caused

You know when the assassin gets caught on fire, ice trap, or those little birds on top her head and even though the effect from those things are gone, im still suffering from the animation, it makes cloaking near impossible as the assassin.

It is caused from a known glitch that will be fixed whenever we finally get the update that is awaiting certification.

The full update details can be found here: http://www.uberent.com/forums/viewtopic.php?f=22&t=2371. The one you want is the second one listed under the General Gameplay section.

Yh tis very annoying, BUT it sometimes can be fixed by experiencing whatever causes the animation.