Guild Wars 2

Well this got fixed:
“Steal: Fixed an issue in which thieves were unable to hit with this ability while using a movement skill.”

However, there is still a really irritating problem with heartseeker—teleport—steal where you get rubber-banded back instead of hitting the target. This can be seen with a heartseeker—infiltrators signet—steal at 20 seconds into this person’s video:
http://www.youtube.com/watch?v=kWjAfzvfQIQ#t=19
This is a combo I use relatively often, and this problem did not happen before the feature patch.

A couple friends and I have been testing it and it seems to be a general issue with movement skills combined with double teleports. There are not a whole lot of examples of this that I know of, but it happens on thief with heartseeker and flanking strike, and it happens on guardian with leap—merciful—judges.

The combo can still work without rubber-banding by doing it very quickly (also demonstrated in the above video). For example, if you heartseeker and immediately (almost at the same time) use the signet and steal, then it will work, but if you wait even slightly into the heartseeker animation before teleporting, you rubber-band. This means you cannot time the double teleport to land the heartseeker and steal at the same time. Instead you are still at the start of your heartseeker animation when you hit the person with steal, which prevents you from bursting as efficiently.

TL;DR
Movement skills (such as heartseeker) combined with double teleport (such as infil. sig. + steal) rubber-band you back and make you a sad panda.