This strangely happens because of the light attack when the enemy is at the side of you. And you want to attack the enemy on the move using light attack and skill.
What you expect:
Your character uses LA and immediately uses the skill while moving.
What you get:
Your character turns and postpones a light attack, using the attacking skill first. The light attack only works after it, and from the moment you pressed the LCM until the light attack starts, you cannot move or roll with WASD
This is very annoying, as there is a high risk of getting killed in active combat without being able to move away from the deadly skill by area. The problem only applies to bows and melee weapons. When using staffs, you do not lose the ability to move, but the light attack will not be replicated.
I recorded a short video showing the keys I pressed:
https://youtu.be/LSGdEpn8YBc