diff --git a/src/TagField.php b/src/TagField.php
index 2a81577..f2a715b 100644
--- a/src/TagField.php
+++ b/src/TagField.php
@@ -566,6 +566,9 @@ public function saveInto(DataObjectInterface $record)
         $fieldName = $this->getName();
         $values = $this->getValueArray();
 
+        // We need to extract IDs as in some cases (Relation) we are unable to use the value field
+        $ids = [];
+
         if (!$values) {
             $values = [];
         }
@@ -585,6 +588,7 @@ public function saveInto(DataObjectInterface $record)
                 continue;
             }
 
+            $ids[] = $tag->ID;
             $cleanValues[] = $tag->{$valueField};
         }
 
@@ -595,7 +599,7 @@ public function saveInto(DataObjectInterface $record)
 
         if ($relation instanceof Relation) {
             // Save values into relation
-            $relation->setByIDList(array_filter($cleanValues ?? []));
+            $relation->setByIDList(array_filter($ids ?? []));
         } elseif ($this->getAllowRawValue()) {
             // Store raw data without serialisation
             $record->{$fieldName} = $cleanValues;
@@ -607,8 +611,23 @@ public function saveInto(DataObjectInterface $record)
                     // ... JSON-encoded string for other fields
                     : $this->stringEncode(array_filter(array_values($cleanValues)));
             } else {
-                $record->{$fieldName} = $tag && $tag->{$valueField}
-                    ? $tag->{$valueField}
+                // Detect has one as this case needs ID as opposed to custom value
+                $relations = $record->hasOne();
+                $hasOneDetected = false;
+
+                foreach ($relations as $relationName => $relationTarget) {
+                    $foreignKey = $relationName . 'ID';
+
+                    if ($foreignKey === $fieldName) {
+                        $hasOneDetected = true;
+
+                        break;
+                    }
+                }
+
+                $targetField = $hasOneDetected ? 'ID' : $valueField;
+                $record->{$fieldName} = $tag && $tag->{$targetField}
+                    ? $tag->{$targetField}
                     : null;
             }
         }
@@ -708,7 +727,7 @@ protected function getTags($term)
         // Map into a distinct list
         $items = [];
 
-        foreach ($list->getGenerator() as $record) {
+        foreach ($list as $record) {
             $value = $record->{$valueField};
             $items[$value] = [
                 'Title' => $record->{$titleField},
diff --git a/tests/Stub/TagFieldTestBlogPost.php b/tests/Stub/TagFieldTestBlogPost.php
index d6db3dd..4e09e65 100644
--- a/tests/Stub/TagFieldTestBlogPost.php
+++ b/tests/Stub/TagFieldTestBlogPost.php
@@ -4,8 +4,14 @@
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\ORM\DataObject;
-use SilverStripe\TagField\Tests\Stub\TagFieldTestBlogTag;
+use SilverStripe\ORM\ManyManyList;
 
+/**
+ * @property string $Content
+ * @property int $PrimaryTagID
+ * @method TagFieldTestBlogTag PrimaryTag()
+ * @method ManyManyList|TagFieldTestBlogTag[] Tags()
+ */
 class TagFieldTestBlogPost extends DataObject implements TestOnly
 {
     private static $table_name = 'TagFieldTestBlogPost';
diff --git a/tests/Stub/TagFieldTestBlogTag.php b/tests/Stub/TagFieldTestBlogTag.php
index e01ea4b..9a8918e 100644
--- a/tests/Stub/TagFieldTestBlogTag.php
+++ b/tests/Stub/TagFieldTestBlogTag.php
@@ -4,8 +4,11 @@
 
 use SilverStripe\Dev\TestOnly;
 use SilverStripe\ORM\DataObject;
-use SilverStripe\TagField\Tests\Stub\TagFieldTestBlogPost;
+use SilverStripe\ORM\ManyManyList;
 
+/**
+ * @method ManyManyList|TagFieldTestBlogPost[] BlogPosts()
+ */
 class TagFieldTestBlogTag extends DataObject implements TestOnly
 {
     private static $table_name = 'TagFieldTestBlogTag';