I also ran into the same problem. Make sure you add the correct MIME types for SVG images to your server. If they are not there or they are not configured correctly, your browser will not display them.
I processed this via .htaccess:
AddType image/svg+xml svg AddType image/svg+xml svgz
If you still cannot get SVG images, you can always change the background images in CSS to use the .png version of the control panel and play the icons.
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