To clarify, using Insert>Object you have the choice with the radio buttons to 'Create New' or to 'Create from File'. I tried both options and neither was working well, at least not using an .xlsx file.
Creating a file in Excel, saving it as a .csv and then using 'Create from File' worked, to a point. All the data would show up but any formatting would have to be done (and possibly redone) through ArcMap after the table had been inserted.