Index: web/modules/contrib/webform/src/Plugin/WebformElement/WebformCheckboxesOther.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- web/modules/contrib/webform/src/Plugin/WebformElement/WebformCheckboxesOther.php	(date 1534508906712)
+++ web/modules/contrib/webform/src/Plugin/WebformElement/WebformCheckboxesOther.php	(date 1534508906712)
@@ -46,14 +46,20 @@
   public function getElementSelectorInputValue($selector, $trigger, array $element, WebformSubmissionInterface $webform_submission) {
     $input_name = WebformSubmissionConditionsValidator::getSelectorInputName($selector);
     $other_type = WebformSubmissionConditionsValidator::getInputNameAsArray($input_name, 1);
-    $value = $this->getRawValue($element, $webform_submission);
+    $value = $this->getRawValue($element, $webform_submission) ?: [];
+
     if ($other_type === 'other') {
       $other_value = array_diff($value, array_keys($element['#options']));
       return ($other_value) ? implode(', ', $other_value) : NULL;
     }
-    else {
-      return array_intersect($value, array_keys($element['#options']));
+
+    $option_value = WebformSubmissionConditionsValidator::getInputNameAsArray($input_name, 2);
+
+    if (in_array($option_value, $value, TRUE)) {
+      return (in_array($trigger, ['checked', 'unchecked'])) ? TRUE : $value;
     }
+
+    return (in_array($trigger, ['checked', 'unchecked'])) ? FALSE : NULL;
   }
 
 }