Hoe to recreate the issue:
1) go to the social sharing tool settings page
2) go to the tab shortcode
3) add Delicious
4) set Large icon (or also Medium...)
5) assign to Custom icon url field an icon to test
To see the icon I've set
What really happens:
Default icon is showed. The custom icon url title became the title of the icon.
Thank you very much for this good plugin and for every effort!