I thought I was optimizing for the search engines. But I just discovered I must do extra work on my Medium articles. All this time I was making sure that my Titles and Subtitles were SEO-friendly. I just looked at the settings and realized that the SEO Description (which you mention in your article) for my article was completely different!

The description grabs words from the beginning paragraph and puts that as the SEO Description. Now I have to comb through my articles and make changes manually. I have 500+ articles. BUMMER!