Enum override seems to have two dropdowns in UI and produces error

[cheesymoo]

Unity Editor version 2020.1.2f1

I also receive this error when the popup window closes from an enum selection:

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.EditorWindow.Close () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorWindow.cs:914)
UnityPickers.ValuePicker`1[T].OnLostFocus () (at Assets/Editor/UnityPickers/ValuePicker.cs:127)
UnityEditor.DockArea.OnDestroy () (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:125)
UnityEditor.EditorWindow:Close()
UnityPickers.ValuePicker`1:OnLostFocus() (at Assets/Editor/UnityPickers/ValuePicker.cs:127)
UnityEditor.EditorWindow:Close()
UnityPickers.ValuePicker`1:Select(Enum) (at Assets/Editor/UnityPickers/ValuePicker.cs:254)
UnityPickers.ValuePicker`1:DrawContent() (at Assets/Editor/UnityPickers/ValuePicker.cs:188)
UnityPickers.ValuePicker`1:OnGUI() (at Assets/Editor/UnityPickers/ValuePicker.cs:122)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:189)