Could you specify your version of your Studio and activity package? I tested it on 2019.1 and the latest UiAutomation activity package v19.1.0 and it seems to be working.
Two clicks with following selectors:
First click:
"<wnd app='iexplore.exe' cls='IEFrame' title='Download Sample DOC Files For Demo Use - Internet Explorer' /><wnd aaname='Notification' cls='DirectUIHWND' /><ctrl automationid='IENotificationBar' /><ctrl name='Open' role='split button' /><ctrl name='6' role='drop down button' />"
And the second click:
"<wnd app='iexplore.exe' cls='#32768' /><ctrl name='Context' role='popup menu' /><ctrl automationid='53412' />"
To click the element in the dropdown, use F2 to delay the selector grab for 3 seconds 
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