Time: 9:30 PM - 10:15 PM CST
Frequency: Reproduced it multiple times in and out of instance, still happening now
World name: Gilgamesh
Character name: Chaliandra Arbeau
NPC name: n/a
Monster name: n/a
Class/Level: 60
Party or solo: Party
In-game time: n/a
Area and coordinates: Thok Ast Thok Extreme, Lavender Beds
Steps:
1. As a White Mage, enter a party with any number of other players.
2. Have all party members target either nothing, or something other than the White Mage.
3. White Mage casts Assize.
4. All party members in range will lose their current target and "soft-target" onto the White Mage. (The small white circle will appear on the WHM's body, not the hard-target ring under the WHM's feet).

My static noticed this bug during Ravana Extreme, during which Assize would cause all party members to untarget the boss, the adds, or the tank (healers).