I tried to add a new client & I got a prompt that this client already exists so I changed the name slightly but neither the old name nor the new one shows up in the open, inactive or closed (or even templates) listings.
Where did they go?
That's really hard to say. I suggest you go up to the top of the screen and click on Special - Text search. Put in part of the name and click on clients to choose the fields to be searched.
*Community Hub is the new name for Sage City