How do certain "multi-hit" skills work?

[Estellios]

You misinterpreted what I meant. My point was that your problem is because you are trying to solo something and they are turning as soon as you move out from in front of them and they aren't mid-skill or asleep, stunned, or bound. There's nothing random or anything about it at all.

If you are in a party and the enemy isn't moving around the rear/flank skills work perfectly fine.

Also don't forget that Bootshine's auto-crit not only requires you to be behind the enemy, but also requires you to be in Opo-opo stance which you only get by going through a combo sequence. You can't open raw with Bootshine and get the auto-crit. If you are soloing, use Steel Peak before you run behind it to do Bootshine and you will get the critical bonus easily. It also lasts long enough that you can even work in a flank skill in most cases.