diff --git a/packages/rrweb-snapshot/src/snapshot.ts b/packages/rrweb-snapshot/src/snapshot.ts
index 2cc2544e..144555e0 100644
--- a/packages/rrweb-snapshot/src/snapshot.ts
+++ b/packages/rrweb-snapshot/src/snapshot.ts
@@ -1012,14 +1012,15 @@ export function serializeNodeWithId(
   } else {
     id = genId();
   }
+
+  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
   }
 
-  const serializedNode = Object.assign(_serializedNode, { id });
-
-  mirror.add(n, serializedNode);
-
   if (onSerialize) {
     onSerialize(n);
   }