Hi All,
After lots of research, it seems at some point HACS changed which broke the background and animated icons link from working. There have been several workarounds which in turn will break upon each update to Waves.
Therefore to assist with providing a standard please update your Waves once you have completed the following
1. Create a folder within the following location
/config/www/waves
2. Download or move ALL the backgrounds and animated images to the above directory
3. Update to the latest 2.4 Waves version
4. Restart/Reload your themes (via Developer Tools -> Services and search for Home Assistant Frontend: Reload Themes)
Thanks, everyone for your patience!