diff -u b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
--- b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
+++ b/src/Plugin/paragraphs/Behavior/ParagraphsStylePlugin.php
@@ -89,7 +89,7 @@
         '#type' => 'select',
         '#title' => $this->t('%group Style', ['%group' => $this->yamlStyleDiscovery->getGroupLabel($group_id)]),
         '#options' => $this->getStyleOptions($group_id, $plugin_default),
-        '#default_value' => $paragraph->getBehaviorSetting($this->getPluginId(), $group_id, $this->configuration['groups'][$group_id]['default']),
+        '#default_value' => $paragraph->getBehaviorSetting($this->getPluginId(), ['styles', $group_id], $this->configuration['groups'][$group_id]['default']),
         '#attributes' => ['class' => ['paragraphs-style']],
       ];
       // Allow empty option in case there is no default style configured.
diff -u b/src/Tests/ParagraphsStylePluginTest.php b/src/Tests/ParagraphsStylePluginTest.php
--- b/src/Tests/ParagraphsStylePluginTest.php
+++ b/src/Tests/ParagraphsStylePluginTest.php
@@ -355,6 +355,9 @@
     // Set the paragraph style to bold.
     $this->drupalPostForm('node/' . $node->id() . '/edit', ['paragraphs[0][behavior_plugins][style][style_wrapper][styles][italic_test_group]' => 'bold'], t('Save'));
     $this->assertRaw('paragraphs-behavior-style--bold');
+    // Assert that the selection is correctly displayed.
+    $this->drupalGet('node/' . $node->id() . '/edit');
+    $this->assertOptionSelected('edit-paragraphs-0-behavior-plugins-style-style-wrapper-styles-italic-test-group', 'bold');
 
     // Disable the bold style.
     $this->drupalGet('admin/reports/paragraphs_collection/styles');