Why isn't a revision showing up in layout builder?

I reverted, but I'm not seeing the page version from the selected save point?

If you decide to use Layout Builder, your saves will become part of the page's Revision tab history, but one thing that may throw you off is if, after you revert a page and look at the Layout tab, you may not see any changes. This is because current Layout Builder configuration is temporarily saved to your browser cache to prevent problems if you accidentally leave the page. You don't want to lose your work so when you select and use a revision point from the Revision tab, the Layout Builder configuration on the site will now be a mismatch of your browser's saved config. 

Layout Builder will assume your browser's configuration and history is the correct version and show that to you; however, that is why you will see the exclamation icon above the "save layout" button. 

Layout Builder's save layout button with an exclamation point indicating that there are changes that have not yet been saved.

Hovering over the button will show you have unsaved changes. These changes are actually what is leftover from your browser configuration. To update what your browser displays and use the latest site configuration from the revision point, click the "Discard changes" button. This will remove the browser config, and you should now see the configuration from the revision.