WordPress 4.9.4 contains a fix for a severe bug which stops automated updates.
Things to note
WordPress 4.9.4 should be appplied to your site(s) in order to address a bug introduced in WordPress 4.9.3 which makes any site that uses automated updates stop updating. You will need to manually update WordPress in order for the automated updates to continue. You can read more by looking at the release notes: https://codex.wordpress.org/Version_4.9.4
If you have not done so already – download the update or simply use your existing installation of WordPress to update your site. Either way – this is an excellent time to make a backup copy of your site(s) before upgrading.