If this is the case, the “wiki” of aThemes Sydney should be updated (https://athemes.com/snippets/replace-social-icons-employees/) so that it reflects the change in Sydney Toolbox and how to change the icons
This is not resolved. The fault exists in the current Sydney Toolbox version. You can not customize the social icons since verison 1.09, this is where you changed the font icons to SVG. A downgrade is not a fix 😉