josephpaulinoph

There is a misconception that if Google sees a meta description on a page it will use that meta description. Matt Cutts explained in one of his videos that they used to only take content from the page body itself and use that in the search results snippet. So little by little, they moved into sometimes using the description that we put into meta description tag as compared to only taking content from within the page which was a long time ago.

If you have any other seo plugins try deactivating it and leave WordPress SEO activated.

Yes, you can have an empty meta description box to each post. But you have to setup a template so the plugin can generate the descriptions for you. Go into the SEO -> Titles menu and set up a template.