I see there have been various discussions on this without resolution.
I initially succeeded to import a Word Outline document but I have tried to add to it by importing another without success.
If I try importing into the 'top' level it sometimes add the file as a note, other times nothing is added.
If I try importing the file into the Thought where I wish to place it nothing imports.
On all attempts I get the message to the effect that it cannot undo the import and I select 'Yes' to continue but the message box at the top of the screen says "importing 0 of 0".
I am running Version 126.96.36.199 and MSWord in Office 2013.