diff --git a/h5p.classes.php b/h5p.classes.php
index 03d5136..a403856 100644
--- a/h5p.classes.php
+++ b/h5p.classes.php
@@ -3056,7 +3056,9 @@ class H5PContentValidator {
     $function = null;
     $field = null;
 
-    if (count($semantics->fields) == 1 && $flatten) {
+    $isSubContent = isset($semantics->isSubContent) && $semantics->isSubContent === TRUE;
+
+    if (count($semantics->fields) == 1 && $flatten && !$isSubContent) {
       $field = $semantics->fields[0];
       $function = $this->typeMap[$field->type];
       $this->$function($group, $field);
@@ -3064,7 +3066,7 @@ class H5PContentValidator {
     else {
       foreach ($group as $key => &$value) {
         // If subContentId is set, keep value
-        if($key == 'subContentId' && $value == TRUE){
+        if($isSubContent && ($key == 'subContentId')){
           continue;
         }
 
diff --git a/js/h5p-content-upgrade-process.js b/js/h5p-content-upgrade-process.js
index 1d886cc..e54dbb7 100644
--- a/js/h5p-content-upgrade-process.js
+++ b/js/h5p-content-upgrade-process.js
@@ -182,7 +182,7 @@ H5P.ContentUpgradeProcess = (function (Version) {
         break;
 
       case 'group':
-        if (field.fields.length === 1) {
+        if (field.fields.length === 1 && field.isSubContent !== true) {
           // Single field to process, wrapper will be skipped
           self.processField(field.fields[0], params, function (err, upgradedParams) {
             if (upgradedParams) {