Compressed duration and swift affliction

Hello, I don't know if I'm having a bug or if I just don't understand how it works so I'm posting here.
I wanted to accelerate earthquake' jagged ground so it explodes quicker and tried compressed duration I (formerly fast forward) and swift affliction. In the tooltip, the duration of jagged ground drop from 4sec to 2.2sec, but when I use the skill, the jagged ground still last for 4 sec before exploding.
What am I misunderstanding? Any idea?