diff --git a/backend/czi_hosted/data_common/data_adaptor.py b/backend/czi_hosted/data_common/data_adaptor.py
index 1ef22061..48cb11e6 100644
--- a/backend/czi_hosted/data_common/data_adaptor.py
+++ b/backend/czi_hosted/data_common/data_adaptor.py
@@ -413,7 +413,7 @@ class DataAdaptor(metaclass=ABCMeta):
         else:
             X = self.get_X_array(obs_selector, var_selector)
             if sparse.issparse(X):
-                mean = X.mean(axis=1)
+                mean = X.mean(axis=1).A
             else:
                 mean = X.mean(axis=1, keepdims=True)
 
diff --git a/backend/server/data_common/data_adaptor.py b/backend/server/data_common/data_adaptor.py
index 720e5166..a32f6219 100644
--- a/backend/server/data_common/data_adaptor.py
+++ b/backend/server/data_common/data_adaptor.py
@@ -416,7 +416,7 @@ class DataAdaptor(metaclass=ABCMeta):
         else:
             X = self.get_X_array(obs_selector, var_selector)
             if sparse.issparse(X):
-                mean = X.mean(axis=1)
+                mean = X.mean(axis=1).A
             else:
                 mean = X.mean(axis=1, keepdims=True)