Since the most recent update, when “icon” only option is selected for social media icons related to posts they show up on the individual posts but the Blog page shows the “share this” round icons in the correct color but the graphic is a square instead of the social media image. On mobile devices it is an oval with no square or graphic inside.
The social sharing functionality is not part of the theme.
If you want the sharing buttons to work in both posts and the theme’s “Blog” template (which is a page) you’ll need to keep the sharing option active on both posts and pages in Jetpack.