You open a module — like the "Social Icons" module which is usually part of the demo content — but it is utterly empty?! You "Save" or "Save & Close", and when you look at your site's frontend the social icons are gone.
Your WYSIWYG editor decided to delete the content.
Use "CodeMirror" or "No Editor" so it doesn't wreck your content without warning.
- User > Manage > Your User ( Image 1)
- Now set the CodeMirror als "default" ( Image 2)