Hi – sadly I’m having the same problem since 12 hours or so ago. Until then all was well. I’m not sure it’s the theme, because all was well even after I installed that a few days ago.
First it allowed me to write the meta description but it wouldn’t save it. Then it wouldn’t allow me to enter anything at all. Now I can’t even enter the focus keyword. At first I thought the issue was that I used two separate keywords. This has to be so because the style I’m referring to on the page (about one of 24 different illustration styles) needs two words, not one. But previous pages I’ve SEO’d have also had two or even three keywords. On these previous pages the meta-description etc is all still fine. It hasn’t disappeared.
Would be very happy to hear any advice. URL is http://www.savyra.com/work/illustration/24-styles/simple-line/
https://wordpress.org/plugins/wordpress-seo/
