What happens behind the scenes:
Monster ability goes off = red indicator pops
1)Game engine registers your position; along with anyone else's position around the ability - this is a number for the engine, like coordinate.
2)You move calculates your position along with everyone else's position < the problem is here. sometimes when you move because the engine is throwing so much information at the server it lags on return to the client.
3) Ability happens in real time; game uses the information last recorded which could be your new position or your original position depending on how much the sever lagged to send the info back and forth.

A quick way to fix a position issue is to after moving out of the indicator quickly cast/use an ability to send a signal that this ability is being used at this coordinate. This is not something that works every time. "60% of the time it works, every time."