Which version of studio are you running? Did you upgrade to this version or did you start your app with it?
Unfortunately Atlas v2.4.0 is not available yet. It should have been released during the Mx 8.5.0 release but due to some unforeseen circumstances we had to postpone the release. The new release date of Atlas 2.4.0 will be the 4th of February. I would recommend you not to use the layout grid yet, as you are missing the related styles.