I'm not sure if this is happening to anyone else. But it seems to happen a lot to me. I've also witnessed this happen with a lot of my friends and maybe a few of you have too.
When fighting some monsters, they will usually use their signature skill, indicated by one of two shapes. Either a long rectangle indicating direct line attack or a circle which indicates an AoE of some sort. It's red in color and can be dodged. Now I'm not sure about the rest of you, but there are instances where I will clearly step out of the red hit marker and yet....I still get hit by the move. This is very frustrating when trying to do higher end dungeons or helping people with Primals. The most notorious being Titan for his ground pound and the worst dungeon I've seen this happen in, Brayflox's Longstop. Aiatar will line you up, you side step and you're still hit. It might be a latency issue on my end I don't know, but I could be wrong. It says my connection for the server is excellent, so I don't think that's quite it. What I also find funny is there is also the same issue in Sunken Temple with the Bee's. Not being able to dodge their Final Sting to where it will one shot even the mightiest of tanks. I watched my friend die in one shot, having 5.3k Health and watched it drop to 0. Now that's just silly.
There's a number of factor's that can contribute to this. But they're also common knowledge when factoring in being hit.
-Timing/Movement Speed (Sprint/Walking) (Biggest Part)
-Position of the Mob
-AoE Size/Overlap
-AoE Duration (When the AoE will go off)
I mean thee are those but there are the more technical ones
-Internet Speed
-Latency/Lag
-Ping MS
Stuff like that I guess is also factored into the mix here.