I find it strange that if I don’t add a featured image to a blog post using the oxygen theme, a blank image placeholder still appears. Do I have to add a featured image to all blog posts? It would make sense to not display the blank image placeholder if a feature image wasn’t used. View my site for an example.
I double-checked with our theme team and what you’re seeing is the intended functionality for the Oxygen theme at WordPress.com. To get the most out of the theme, you’ll need to set a featured image for each post.