diff --git a/neurostore_sdk/models/analysis_common.py b/neurostore_sdk/models/analysis_common.py
index 76fdd41..3d41a13 100644
--- a/neurostore_sdk/models/analysis_common.py
+++ b/neurostore_sdk/models/analysis_common.py
@@ -69,6 +69,11 @@ def to_dict(self):
         if self.order is None and "order" in self.__fields_set__:
             _dict['order'] = None
 
+        # set to None if metadata (nullable) is None
+        # and __fields_set__ contains the field
+        if self.metadata is None and "metadata" in self.__fields_set__:
+            _dict['metadata'] = None
+
         return _dict
 
     @classmethod
diff --git a/neurostore_sdk/models/analysis_request.py b/neurostore_sdk/models/analysis_request.py
index e97edb7..d33356e 100644
--- a/neurostore_sdk/models/analysis_request.py
+++ b/neurostore_sdk/models/analysis_request.py
@@ -99,6 +99,11 @@ def to_dict(self):
         if self.order is None and "order" in self.__fields_set__:
             _dict['order'] = None
 
+        # set to None if metadata (nullable) is None
+        # and __fields_set__ contains the field
+        if self.metadata is None and "metadata" in self.__fields_set__:
+            _dict['metadata'] = None
+
         return _dict
 
     @classmethod
diff --git a/neurostore_sdk/models/analysis_return.py b/neurostore_sdk/models/analysis_return.py
index 65a1d15..705e892 100644
--- a/neurostore_sdk/models/analysis_return.py
+++ b/neurostore_sdk/models/analysis_return.py
@@ -121,6 +121,11 @@ def to_dict(self):
         if self.order is None and "order" in self.__fields_set__:
             _dict['order'] = None
 
+        # set to None if metadata (nullable) is None
+        # and __fields_set__ contains the field
+        if self.metadata is None and "metadata" in self.__fields_set__:
+            _dict['metadata'] = None
+
         return _dict
 
     @classmethod