MabiPro: The Authentic Old-School Mabinogi Experience

I've been noticing mobs doing this strange sort of thing where if they aggro, and run up to attack you, their animation won't play and you'll be instantly hit the moment they get within melee range. Every mob I've encountered has done this at least once.

I recreated it in this youtube video, it's not very hard to get to happen.
Did this kind of thing happen on live? Or is this something new to the private server? Or is this just a "me" problem?
Regardless, it's very frustrating to have to play against.

https://youtu.be/hPBwcXp-jn8