Enfold settings won't save, Avia Layout Builder won't load content.

Our host recently updated to PHP 7.3 from PHP 5. Now Enfold settings won’t save. We get a failure message. Also the Avia Layout Builder won’t load content, it just spins the loading icon.

We’ve updated Enfold to the latest version. We’ve disabled all plug-ins and still get the same errors.
We are getting 403 errors in the browser: POST https://telemus.com/wp-admin/admin-ajax.php 403
send @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:4
ajax @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:4
convertTextToInterface @ avia-builder.js?ver=5.2.4-4.7.1.1:1272
set_up @ avia-builder.js?ver=5.2.4-4.7.1.1:125
$.AviaBuilder @ avia-builder.js?ver=5.2.4-4.7.1.1:108
(anonymous) @ avia-builder.js?ver=5.2.4-4.7.1.1:1901
i @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:2
fireWith @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:2
ready @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:2
J @ load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,jquery-ui-core,jquery-ui-widget,utils,moxiejs,plupload&ver=5.2.4:2

Any thoughts on how to fix this?
Thanks