Builder-template sections disappear after editing…

Since at least version 1.9.2 whenever we go to edit a page that uses the builder-template and make even the most minor edit of a panel or a slider and either preview the page or update and save it, the Make builder sections (banner, panels, columns, etc.) disappear completely or do not load. There is no error on the page and apparent way to recover the without restoring the page from a previous backup.

I updated to version 1.9.3, then 1.9.4 hoping that the issue would be resolved. I tested each version on the staging server with a fresh copy of the site. I am running the latest version of WordPress, I’m hosted on WP-Engine and I subscribe to the Plus version of the theme and have the latest version of the Plus plugin. I disabled other plugins to no avail.

Below is the error message I get in the Chrome developer tool console after I update a page using the builder-template. It appears on any page that I edit using the builder-template. The error does not appear until after I save the page from the edit/admin screen, not the public facing web page, where there are no errors. I tried editing the site in incognito mode and on a different computer and still get the same results.

settings_master.js?ver=1.9.4:349 Uncaught TypeError: Cannot read property 'prototype' of undefined
    at Object.<anonymous> (settings_master.js?ver=1.9.4:349)
    at E (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)
    at Object.r [as extend] (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)
    at model (builder.js?ver=1.9.4:10)
    at panels.js?ver=1.9.4:265
    at E (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)
    at r (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)
    at postlist.js?ver=1.9.3:102
    at E (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)
    at r (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable,jquery-ui-position,underscor&load[]=e,backbone,wp-util,wp-backbone,media-models,plupload,wp-plupload,mediaelement,wp-mediaelement,media-views,editor,farbtastic,jque&load[]=ry-ui-tooltip&ver=4.8.1:70)

The link to the page I shared above is just one example. There should be a big banner across the top, but it is gone. In the meantime, we cannot edit any of the pages using the builder-template on the site because it would break the site. My theme subscription is not up for renewal until 03/16/2018.

The page I need help with: [log in to see the link]