diff -u b/core/modules/outside_in/js/outside_in.es6.js b/core/modules/outside_in/js/outside_in.es6.js
--- b/core/modules/outside_in/js/outside_in.es6.js
+++ b/core/modules/outside_in/js/outside_in.es6.js
@@ -206,7 +206,7 @@
       Drupal.ajax.instances
         // If there is an element and the renderer is 'off_canvas' then we want
         // to add our changes.
-        .filter(instance => $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
+        .filter(instance => instance && $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
         // Loop through all Ajax instances that use the 'off_canvas' renderer to
         // set active editable ID.
         .forEach((instance) => {
@@ -215,7 +215,7 @@
       Drupal.ajax.instances
         // If there is an element and the renderer is 'off_canvas' then we want
         // to add our changes.
-        .filter(instance => instance && $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
+        .filter(instance => $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
         // Loop through all Ajax instances that use the 'off_canvas' renderer to
         // set active editable ID.
         .forEach((instance) => {
reverted:
--- b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
+++ a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
@@ -243,10 +243,6 @@
     $this->click($block_selector);
     $this->waitForOffCanvasToOpen();
     $this->assertOffCanvasBlockFormIsValid();
-    // Confirm the Contextual link container is also the active editable now.
-    $this->assertSession()->elementExists('css', "$contextual_link_container.outside-in-active-editable");
-    // Assert that no other element is set as active.
-    $this->assertEquals(1, count($this->getSession()->getPage()->findAll('css', '.outside-in-active-editable')));
   }
 
   /**
diff -u b/core/modules/outside_in/js/outside_in.es6.js b/core/modules/outside_in/js/outside_in.es6.js
--- b/core/modules/outside_in/js/outside_in.es6.js
+++ b/core/modules/outside_in/js/outside_in.es6.js
@@ -206,7 +206,7 @@
       Drupal.ajax.instances
         // If there is an element and the renderer is 'off_canvas' then we want
         // to add our changes.
-        .filter(instance => $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
+        .filter(instance => instance && $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
         // Loop through all Ajax instances that use the 'off_canvas' renderer to
         // set active editable ID.
         .forEach((instance) => {
@@ -215,7 +215,7 @@
       Drupal.ajax.instances
         // If there is an element and the renderer is 'off_canvas' then we want
         // to add our changes.
-        .filter(instance => instance && $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
+        .filter(instance => $(instance.element).attr('data-dialog-renderer') === 'off_canvas')
         // Loop through all Ajax instances that use the 'off_canvas' renderer to
         // set active editable ID.
         .forEach((instance) => {
reverted:
--- b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
+++ a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
@@ -243,10 +243,6 @@
     $this->click($block_selector);
     $this->waitForOffCanvasToOpen();
     $this->assertOffCanvasBlockFormIsValid();
-    // Confirm the Contextual link container is also the active editable now.
-    $this->assertSession()->elementExists('css', "$contextual_link_container.outside-in-active-editable");
-    // Assert that no other element is set as active.
-    $this->assertEquals(1, count($this->getSession()->getPage()->findAll('css', '.outside-in-active-editable')));
   }
 
   /**