O.K. If you have a message in your record requesting an upgrade (I assume for a customer service recovery reason or somesuch) then do NOT OLCI and make sure you go to a manned desk. The agent will then see the message and call whoever they call.

For reasons I won't go into here I was - once upon a time - able to request the occasional space available upgrade. OLCI meant the request wasn't picked up - going to a check in desk ensured it was.

That flight could well be oversold, but I don't know the route, date etc so it's not easy to speculate.