issue with exported & re-imported animations, help needed

hello, i’m working on a third person shooter, i’m trying to create strafing animations from the basic walk & run animations from the third template project.

this is what i have done:

  1. i opened the walk animation, turned the root 90 degrees, then a rotate the pelvis and the neck to see the mannequin strafe walking but with the head looking front.
  2. i recorded that to a new animation, because the recording has some blank keys at the beginning & the end (i don’t know how to remove these blank keys, using ue4, to reduce the animation to the exact keys that the animation is using) i exported the animation to a fbx to edit the fbx with 3dmax.
  3. in 3dmax i removed the blank keys from the beginning and from the end to let the animation be the exact lenght of the clip (i setup the 3dmax using the units for ue4)
  4. i exported the animation with the fixed lenght to fbx and reimported it again to ue4 choosing it’s original skeleton.
  5. i put my strafe animation on my blend space.

after all these steps my strafe(s) aniamtion has a weird behavior, don’t know why, when the player is strafing the models will reduce it’s size and when it return to idle, walk or normal run it return to it’s normal size.

here is a video that shows the problem

i don’t kno why is this happening, i didn’t change the scale of the model in 3d max, i only had removed the empty space from the animation clip.

i tried importing the complete asset and only the animation and the result were the same.

any help will be very useful.

thanks in advance for all your help

p.s.: if someone know how to remove the empty space from the beginning and the ending of the clip into ue4, that will be useful too because know that i don’t need to export the clip to 3dmax and that will avoid the scale problem.