If you have Third-Party Cookies disabled in your browser, you may get the following error after clicking Save & Publish: Your session has expired. Refresh this page and try again. The fix involves updating your browser settings to enable Third-Party cookies.
This post has info on where to change the setting for Firefox: https://support.mozilla.org/en-US/kb/disable-third-party-cookies Instead of setting to Never, you will need to set to Always.
Optionally, you could edit your page directly on the Landable website (http://landable.co).