@Etroka to answer your question, you need to uninstall the Yoast and install a new one. mine is working perfectly well. also, ensure you add your meta description from the title & metas indicated on the plugin.
now to get a good SEO, in your article your keyword should appear atleast 5 to 6 times, it should appear at:
1. the beginning of your title post, and first paragraph.
2. ensure your image has alt text with the same keyword.
3. do not write less than 300 words.
you can get more tips on SEO here
see a sample of a good SEO here
I’m an SEO analyst feel free to contact me through my website
