For that WP boss it might be that the boss has targeted you? When that happens with adds up all the adds will instantly turn on you too. But really they should not be a problem for a White Mage you should WANT them to aggro on you. Before each add spawn make sure you have stoneskin on yourself and the tank then divine seal and regen on tank and yourself, Go into cleric stance and wait for adds. They will swarm you. Use Holy and it will stun them then just spam Holy a few times and they'll die while trying to break your stoneskin.

After they die use shroud to regen mana if you have a bard ask for their mana regen buff. Heal tank reapply stoneskin and rinse and repeat. Holy is so insane on the adds for that boss it destroys them.