Reposting the information since it was lost from the original post:
With 1.17 a new animation got added called "TailScale". Since most of the custom animations doesn't have this, they will just crash the game.
To make them work you (or the creator of the animations) just has to add this one animation to the skeleton.
In this post I'll show you the fastest way of doing this.
First off all you will need Ogre command line tools. (https://sourceforge.net/projects/ogre/files/ogre-tools/1.7.2/OgreCommandLineTools_1.7.2.zip/download)
Extract the zip to somewhere.
Grab your custom skeleton file and pull it over OgreXMLConverter.exe. A black window will pop up and when it disappears you should have a f/cbody.skeleton.xml next to your original skeleton file.
Open it up in a text editor (notepad for example) and search for <animations>.
Hit an enter (so you have an empty line after <animations>) and paste everything from the respective text files in:
canines: https://drive.google.com/file/d/1HYsjjD-QPPpkaEUpR_wIddmTUTjLmpDe/view
felines: https://drive.google.com/file/d/1mwH234_c6tAprHgIaXMKYuTImrnlm-az/view
Save the .skeleton.xml and convert it back with the XML converter. You should see the newly converted c/fbody.skeleton popping up.
Copy it into your game and you should be all set and done.