In case someone finds this in the future, a common issue with Microsoft IIS servers is they are not configured for several file extensions that are in common use, like webp images, svg vector files, woff/woff2 font files. It’s like IIS is stuck in the 90s. Anyway the real issue is IIS won’t just serve the file as is, it will produce an error, so the images and fonts won’t load.
The fix is to add a web.config file at the top level of the website, using the web host control panel.