Game Mechanics: Plane of Fear - Not able to see/target player Bug

[ElanoraBryght]

Two separate occasions in Plane of Fear I have had a bug where a player is invisible to me / not able to be targeted. The first time I was not grouped with the player, the second time I was. My dying (leaving zone and coming back) or their dying did not fix.

Ways I attempted to target :
/rt
/target (Players Name)
Having other player open trade window with me - they were not able to do so
Using the appropriate F# key when grouped with the player
Assisting another player who was targeting them.

The time I was grouped with the other player, she appeared to be out of the zone; her health bar in the group window was grayed out all night. Her pet registered as an NPC to me; using Z and Cntl Z to cycle through nearest NPCs, I repeatedly targeted her pet for the time we were in Fear.

Both times I was the only person who seemed to have this problem. The other player could see and target me.