After migrating to Ghost 1.0 and Casper 2.0 (I'm actually on Ghost Version 1.13.0 and Casper Version 2.1.4), social sharing buttons are completely missing.
At first I thought they had been removed from the theme, since they usually have been on the footer. Instead they are inside an hidden floating-header
div on the top of the page that is hidden by default, and should become visible after some scroll on the page.
It seems to be a javascript conflict that prevents the function that change the CSS from running.
After some searching, I discover the problem was a conflict with the jquery <script>
tag left in the Code Injection screen since Ghost 0.7 version.
Just remove the jquery <script>
tag to fix the problem and have back the floating-header
div with social sharing buttons.