diff --git a/inc/class-registration.php b/inc/class-registration.php
index fff5da32a..14adcfb45 100644
--- a/inc/class-registration.php
+++ b/inc/class-registration.php
@@ -529,16 +529,8 @@ public function enqueue_dependencies( $post = null ) {
 		$this->enqueue_block_styles( $post );
 
 		if ( has_block( 'core/block', $post ) ) {
-			$blocks = parse_blocks( $content );
-			$blocks = array_filter(
-				$blocks,
-				function ( $block ) {
-					return 'core/block' === $block['blockName'] && isset( $block['attrs']['ref'] );
-				}
-			);
-
-			foreach ( $blocks as $block ) {
-				$this->enqueue_dependencies( $block['attrs']['ref'] );
+			foreach ( self::get_reusable_block_ids( parse_blocks( $content ) ) as $ref ) {
+				$this->enqueue_dependencies( $ref );
 			}
 		}
 
@@ -1230,6 +1222,35 @@ public static function get_active_widgets_content() {
 		return $content;
 	}
 
+	/**
+	 * Collect the IDs of every reusable block (synced pattern) in a block tree.
+	 *
+	 * Synced patterns can be nested inside other blocks, so the whole tree is
+	 * walked instead of only its top level. Without this, a pattern placed inside
+	 * a Group block is never found and the blocks it holds get none of their
+	 * assets registered.
+	 *
+	 * @param array<int, array<string, mixed>> $blocks Parsed blocks.
+	 * @return array<int, int> List of reusable block IDs.
+	 * @since   3.2.3
+	 * @access  public
+	 */
+	public static function get_reusable_block_ids( $blocks ) {
+		$ids = array();
+
+		foreach ( $blocks as $block ) {
+			if ( 'core/block' === $block['blockName'] && isset( $block['attrs']['ref'] ) ) {
+				$ids[] = (int) $block['attrs']['ref'];
+			}
+
+			if ( ! empty( $block['innerBlocks'] ) ) {
+				$ids = array_merge( $ids, self::get_reusable_block_ids( $block['innerBlocks'] ) );
+			}
+		}
+
+		return array_values( array_unique( $ids ) );
+	}
+
 	/**
 	 * Watch and save the used widgets.
 	 *
diff --git a/tests/test-registration.php b/tests/test-registration.php
index d12b2983c..12d2b920b 100644
--- a/tests/test-registration.php
+++ b/tests/test-registration.php
@@ -244,4 +244,38 @@ public function test_register_blocks_survives_dynamic_renderer_class_whose_file_
 		$this->assertFalse( class_exists( $class, false ), 'The renderer class must not have been defined.' );
 		$this->assertCaptchaRegisteredWithoutRenderer();
 	}
+
+	/**
+	 * A synced pattern nested inside another block must still be found: the blocks
+	 * it holds get none of their assets registered otherwise.
+	 */
+	public function test_reusable_block_ids_finds_a_nested_pattern() {
+		$content = '<!-- wp:group --><div class="wp-block-group"><!-- wp:block {"ref":42} /--></div><!-- /wp:group -->';
+
+		$this->assertEquals( array( 42 ), Registration::get_reusable_block_ids( parse_blocks( $content ) ) );
+	}
+
+	/**
+	 * Patterns are collected from every level, each ID only once.
+	 */
+	public function test_reusable_block_ids_collects_every_level_without_duplicates() {
+		$content = '<!-- wp:block {"ref":1} /-->'
+			. '<!-- wp:group --><div class="wp-block-group">'
+			. '<!-- wp:columns --><div class="wp-block-columns">'
+			. '<!-- wp:column --><div class="wp-block-column"><!-- wp:block {"ref":2} /--></div><!-- /wp:column -->'
+			. '</div><!-- /wp:columns -->'
+			. '<!-- wp:block {"ref":1} /-->'
+			. '</div><!-- /wp:group -->';
+
+		$this->assertEquals( array( 1, 2 ), Registration::get_reusable_block_ids( parse_blocks( $content ) ) );
+	}
+
+	/**
+	 * Content without patterns yields nothing, and a pattern block without a ref
+	 * attribute is skipped rather than producing a bogus ID.
+	 */
+	public function test_reusable_block_ids_is_empty_without_usable_patterns() {
+		$this->assertEquals( array(), Registration::get_reusable_block_ids( parse_blocks( '<!-- wp:paragraph --><p>Text</p><!-- /wp:paragraph -->' ) ) );
+		$this->assertEquals( array(), Registration::get_reusable_block_ids( parse_blocks( '<!-- wp:block /-->' ) ) );
+	}
 }