The auto-list options is disabled in Mtext editor, how can I bring it back?

In the Registry Editor(Window->Run->Regeidt), Edit->Find "NumberingDisabled", it normally under the registry key of

"HKEY_USERS\xxxx\Software\Autodesk\AutoCAD\Rxxxx\ACAD-xxxx:xxx\MTEXT"

Double-click "NumberingDisabled" and change the "Value data" to 0.