Some AOEs don't show the red enemy AOE indicator/marker. This is very unhelpful in PVP as it is hard to tell when you are in some AOEs, especially those which are barely visible like Permafrost. Even those which have an obvious graphic, there is no way to tell whether it is a friendly or hostile AOE without the indicator, so this is an essential functionality and should be fixed.
For example, Twisting Path DOES show the indicator (default red), but Wall of Elements DOESN'T. Some others that DON'T indicate include: Permafrost, Time Stop, Negate, Nova, and probably more.