When you create a new menu item it shows immediately in the menu. Still the menu item is showing as OFF in the menu manager.
Once you manually update the status to on and back to off it behaves.
I see that when creating a new item the setting value5 in tp_variables is set to '-1'
'On' sets it to 0
'Off' sets it to 1
I cannot find where the default is set: but I think the default for a new item should be set to 1 (database default value for the field is -2 btw)