diff --git a/packages/rrweb-snapshot/src/snapshot.ts b/packages/rrweb-snapshot/src/snapshot.ts
index 38df3b6954..277f6e5951 100644
--- a/packages/rrweb-snapshot/src/snapshot.ts
+++ b/packages/rrweb-snapshot/src/snapshot.ts
@@ -1014,14 +1014,15 @@ export function serializeNodeWithId(
   } else {
     id = genId();
   }
-  if (id === IGNORED_NODE) {
-    return null; // slimDOM
-  }
 
   const serializedNode = Object.assign(_serializedNode, { id });
-
+  // add IGNORED_NODE to mirror to track nextSiblings
   mirror.add(n, serializedNode);
 
+  if (id === IGNORED_NODE) {
+    return null; // slimDOM
+  }
+
   if (onSerialize) {
     onSerialize(n);
   }