diff --git src/js/_enqueues/wp/customize/selective-refresh.js src/js/_enqueues/wp/customize/selective-refresh.js
index 82d0f9e8d6..1b2d16bb36 100644
--- src/js/_enqueues/wp/customize/selective-refresh.js
+++ src/js/_enqueues/wp/customize/selective-refresh.js
@@ -660,7 +660,8 @@ wp.customize.selectiveRefresh = ( function( $, api ) {
 			nonce: api.settings.nonce.preview,
 			customize_theme: api.settings.theme.stylesheet,
 			customized: JSON.stringify( dirtyCustomized ),
-			customize_changeset_uuid: api.settings.changeset.uuid
+			customize_changeset_uuid: api.settings.changeset.uuid,
+			customize_messenger_channel: api.settings.channel,
 		};
 	};