diff --git a/langfuse/_task_manager/media_manager.py b/langfuse/_task_manager/media_manager.py
index 43a50f8c6..a7cbd05d7 100644
--- a/langfuse/_task_manager/media_manager.py
+++ b/langfuse/_task_manager/media_manager.py
@@ -121,9 +121,10 @@ def _process_data_recursively(data: Any, level: int):
                     field=field,
                 )
 
-                data["data"] = media
+                copied = data.copy()
+                copied["data"] = media
 
-                return data
+                return copied
 
             # Vertex
             if (
diff --git a/tests/test_openai.py b/tests/test_openai.py
index a1ef79a2e..86b0f057c 100644
--- a/tests/test_openai.py
+++ b/tests/test_openai.py
@@ -1,5 +1,6 @@
 import importlib
 import os
+from time import sleep
 
 import pytest
 from pydantic import BaseModel
@@ -36,6 +37,8 @@ def test_openai_chat_completion(openai):
 
     langfuse.flush()
 
+    sleep(1)
+
     generation = get_api().observations.get_many(
         name=generation_name, type="GENERATION"
     )