Multi Sphere Trace

Hi. Im trying to study Behavior Tree. Current problem is a Multi Sphere Trace for Objects in my service.

This is the setting:

Here is the Blueprint, which is modified version of https://docs.unrealengine.com/latest/INT/Engine/AI/BehaviorTrees/QuickStart/11/index.html

If i enable XCharacter/Player character to actors to ignore list, Sphere Trace wont detect anything. If i disable it, it wont detect anything, unless player character is inside the sphere and behind the actor ball or pawn ball. Desired Object Types is set to pawn. Sphere Trace By Channel works better, but i just want know why trace by objects wont work.

Thx for the help.