unhide previously hiden HDAdditionalReflectionData

com.unity.render-pipelines.high-definition/HDRP/Editor/Lighting/Reflection/HDReflectionProbeEditor.cs

 
             HDAdditionalReflectionData probe = (HDAdditionalReflectionData)m_AdditionalDataSerializedObject.targetObject;
             probe.influenceVolume.Init(probe);
+
+            //unhide previously hidden components
+            probe.hideFlags = HideFlags.None;
         }
     }
 }