I created a character using Character Manager, everything is default, nothing has been edited. The only thing I did was replace a new Jump Start animation from Gruzam's Powerful Sword Pack.
And the error happened as shown in the video attached in the this link
I also attached the animation so you can reproduce the error.
Unity 2021.3.21f
And the error happened as shown in the video attached in the this link
I also attached the animation so you can reproduce the error.
Unity 2021.3.21f