Unreal artv1 Maya wrong animation moves in decimal frames after export fbx

I have a problem with artv1.
I make my animation in Maya with artv1 mannequin at 30fps like video below. It seems no any problem.

But when i export animation as fbx format and import maya again or import unreal engine, mannequin feet bone make moves that i didn’t made at decimal frames. for example in between 1frame and 2 frame like 1.512 etc… 2 videos below.

May be it looks not very important but it bothers me.

You know how can i fix this ?