docarray
diff --git a/docarray/index/backends/mongodb_atlas.py b/docarray/index/backends/mongodb_atlas.py
@@ -563,16 +563,18 @@ def _vector_search_stage(
         max_candidates = self._get_max_candidates(search_field)
         query = query.astype(np.float64).tolist()
 
-        return {
+        stage = {
             '$vectorSearch': {
                 'index': search_index_name,
                 'path': search_field,
                 'queryVector': query,
                 'numCandidates': min(limit * oversampling_factor, max_candidates),
                 'limit': limit,
-                'filter': {"$and": filters} if filters else None,
             }
         }
+        if filters:
+            stage['$vectorSearch']['filter'] = {"$and": filters}
+        return stage
 
     def _text_search_stage(
         self,

diff --git a/tests/index/mongo_atlas/__init__.py b/tests/index/mongo_atlas/__init__.py
@@ -29,7 +29,7 @@ class FlatSchema(BaseDoc):
     embedding2: NdArray = Field(dim=N_DIM, index_name="vector_index_2")
 
 
-def assert_when_ready(callable: Callable, tries: int = 5, interval: float = 2):
+def assert_when_ready(callable: Callable, tries: int = 10, interval: float = 2):
     """
     Retry callable to account for time taken to change data on the cluster
     """