This bug affects version 9.0.0. If you create a statue with the chisel but don't change its animation, the animation will be Idle by default as of version 9.0.0 (it would be Walking by default in previous versions), but if you exit and reenter that world, the animation will change to the walking animation.

I noticed this bug when creating the group photo screenshots for my most recent suggestion to the suggestion forum, because all the statues in those screenshots had their walking animations when I entered the world today even though they had their idle animations when I took the photos. I think this bug is easy to notice with Hisuian Sliggoo, because Sliggoo's idle animation (shell laying on the ground with Sliggoo's head poking out) is much different than its walking animation (rolling around on the shell like a rolling coin). It is also quite easy to notice with Kantonian Vulpix because it sits in its Idle animation.

Here is a video showing this bug:
https://imgur.com/a/pPkWkTk

How to reproduce:
1) Give yourself a chisel.
2) Use the chisel on the ground.
3) Set the Pokemon to be Sliggoo and set the Form to Hisuian.
4) Do not touch the animation. Notice that the animation is Idle by default.
5) Click "Save".
6) Exit the world.
7) Reenter the world.
8) Notice that Sliggoo now has its Walking animation.

Tested using The Pixelmon Modpack Beta on Curseforge, with no external JSONs enabled.

I tested it here and confirmed the bug you passed, thank you very much for the ticket.

forwarded :)

This issue was fixed in 9.0.6. If this continues to be an issue, please open a new ticket.