I forgot to change the m_observationType

com.unity.ml-agents/Editor/VectorSensorComponentEditor.cs

                 // These fields affect the sensor order or observation size,
                 // So can't be changed at runtime.
                 EditorGUILayout.PropertyField(so.FindProperty("m_SensorName"), true);
-                EditorGUILayout.PropertyField(so.FindProperty("m_observationSize"), true);
+                EditorGUILayout.PropertyField(so.FindProperty("m_ObservationSize"), true);
                 EditorGUILayout.PropertyField(so.FindProperty("m_ObservationType"), true);
             }
             EditorGUI.EndDisabledGroup();