The plugin updates count is frozen on WordPress.
That is an annoying issue that sometimes is not resolved after the update of the respective plugins.
A solution would be to reinstall WordPress which is too drastic.
In fact it comes from the cache of your Internet browser, you have to purge it by erasing the caching.
In Chrome > Settings > More tools > Erase the browser data > Pictures and files in cache > Clear the browser data. Then restart your browser or post a new article.