Bug Selecting an object when animating overrides its position globally

I have a sliding animation (from Mixamo) for a generic character (non-humanoid), this animation consist mostly of rotations (since the rig is humanoid-like just generic).
Unity version: Unity 2019.3.13f1

Here's a video of the bug:

• First I show you how the animation is supposed to be
• Then I select the Left Arm, and play the animation, the first time it plays the same as before, then I stop it an play it again and the arm gets shifted and stays in that position
• Then I deselect the character so it goes back to its default position (T-Pose) but the Left Arm stays distorted like before
• Lastly I proceed to reset the position of the Left Arm in the inspector manually

 

Also I tried creating an animation from scratch by positioning/rotating "bones" of the rig and setting key frames, but as soon as I moved to the next frame everything reset inside the animation, I deselected the gameobject and then discovered that it moved globally and not inside the animation...