Guardians and dungeons
Wall of Reflection works against projectiles, but fails against cones and AoE moves. But, it never claimed to reflect those in the first place.
Sanctuary’s knockback is considered a form of crowd control, which triggers the boss “stack CC resistance” buff. I’ve kept a boss sitting in my Sanctuary field, and he’ll get knocked down, gain his resistance stack, and then that stack will burn away while he stays in Sanctuary until eventually the boss is knocked down again.