Check if any animation files are missing in the game folder. Sometimes, a missing file can cause the list to be empty. If you're modifying the game or using a mod, there might be a conflict or an error in the custom script.
You can also do this to delete Ren'Py saves and start from scratch:
Close the game, press Windows + R, type %appdata%, and hit Enter. This will open the AppData\Roaming folder. Then manually enter the folder named RenPy (sometimes it doesn’t open directly). There you'll see folders for the games you've played. Delete the folder for the game (for example, WitchHunter) to remove all save files.
Next, go to the folder where the game is installed and also delete any saves found there (usually in a subfolder called saves).
Finally, download the game again from F95Zone, without any mods or modifications. This ensures you have a clean installation with no weird errors.