"Preview Changes" still doesn't seem to work

I’ve added these lines to the wp-config:

define( 'CFS_REVISIONS', true );
define( 'WP_POST_REVISIONS', 5 );

Which turns on and limits revisions, and appears to be working correctly. However, when making a change without saving and clicking ‘preview changes’, the changes to the CFS fields don’t show up.

Thoughts?

https://www.ads-software.com/plugins/custom-field-suite/