Hello,
I encountered this issue as well where the sdxl styles images wouldn't load because of the case sensitivity of filenames on the Linux version of Fooocus; the current behavior attempts to use the Camel Case name to display the images.
I worked around the issue by editing line 1103 on viewer.html and adding toLowerCase():
<div class="flex-initial text-center mx-1 styleContainer">
<img src={ ("/file=sdxl_styles/samples/"+style.toLowerCase().replace(/ /g,"_")+".jpg") } class="styleImage"/>
<span class="styleTitle">{style}</span>
Here's a screenshot of the file listing:
