[Bug]} Mystic/Defiler Group Ward in PVP

Hello
Since the latest major PVP GU was launched, the Mystic's group ward, Umbral Warding overwrites Defilers group ward Carrion Warding. Pre-GU it used to be, whoever had the highest/biggest group ward, had priority. Now a low-level Mystics group ward, will prevent defilers from casting/landing their group ward.
Example:
1. If Umbral Warding is up, when I try to cast Carrion Warding I receive the message - "The spell could not take effect"
2. If Carrion Warding is up, and a Mystic joins the group and cast Umbral Warding, it replaces Carrion Warding, even though the ward is much smaller/weaker.
For those of you that think - well does it matter which one of the classes that has the group ward up? Yes it does matter - the heal linked with the grp ward is essential, and also it refreshes Ancestral Channeling.
Long story short, it is very difficult to heal as a defiler when grouped with a Mystic in PVP.
DEV comment please..

It has to do with their prestige that gives them an upgraded group ward. Yes it's very annoying that a defiler can't even cast his group ward at all if a mystic is in the group.