Although you have spoke with our Phone Support, I wanted to make sure we shared our response here as well. We have seen this experience happen to users using Safari as you are. It is however usually caused from Prevent cross-site tracking being enabled. If you have this setting enabled, please click Safari > Preferences > Privacy > if Website Tracking : Prevent cross-site tracking is checked, deselect it and try again. Does deselecting this setting help? Our Webiste Builder team also has this help article with more potential workarounds.