Children Ghosts Walking up / down stairs has broken animation

Children Ghosts who use a staircase have a jumpy / broken animation

https://drive.google.com/file/d/1KKd0qV5ELWCbgXtMy6KEB5sNaptnnN5A/view?usp=drive_link 

Please watch the video, it is happening on a vanilla game 

EDIT by crinrict: No changes, just made sure link works as link