Question VFX world space work different when it has a parent or not.

VFX wolrd space work different when it has a parent or not.
What I have:

· a VFX using world space

· a explosion velocity from target position

· vfx has a parent

· the parent is bind to the target position
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When parent in position (0,0,0), it works fine:
but when I move the parent, the explosion speed center seems did not move(or move slow than the vfx it does), so the particles tends to move towards a center direction but not like a "explode" one.

 

when I move the parent:

 

all the particle have addition speed towards moving direction.

 

And if I let vfx become a single obj without parent, and move vfx to 0,0,0
It works fine:

 

thank you. I'll check it.