Thanks for writing in!
There is no preview because there is a JS error in your blog index. Please clear your cache first or temporarily disable W3 Total Cache for a moment. Please be advised that the settings in X > Theme Options > Blog will allow you to change the style and layout settings, number of columns for masonry layout and add Post Metas. You also have the option to display full post on blog index. If you want to add more that is not in the options, it might be possible with custom development.
By the way, when you edit a post the "Edit in Cornerstone" has disappeared? The "Edit in Cornerstone" must have been disabled which is common if you just updated to the latest version of the theme. To enable it back, please go to the Permissions section in X > Settings > Permissions . To know more about this new feature Permissions, please check this out: https://theme.co/apex/forum/t/permissions/32879/1
Hope this helps.