Post image on Mobile app.

When I create a blog post on my website it always gives me the option to add an image first and foremost before I create the blog. When it is complete, the blog should have an image that I can click on that takes me to the blog post. I can do this on desktop with no problems but I’m having issues with this on the mobile app. It doesn’t give me that option. So when I complete a post, it’s without a header image. Any help?