Hi, this is quite an old topic but faced with apparently hidden group outline symbols the CTRL+8 is a real life saver.

I appear to have hidden it by accident in Excel 2010 and had no idea why it seemed impossible to make any groups.
Very annoying and confusing. And a definite time wasting opportunity.

Also, why is there no ribbon or menu item for it.
Aah, I see ! I should have known to take a look at the advanced options, Show outline symbols if an outline is applied.
How foolish of me, I so dim...