I hope aerolotto works out for you.
As has been posted here before (perhaps even by me), when you are upgraded/waitlisted for an upgrade on the second leg of a connection, the system does not know which booking (original or u/g) to associate the first leg with, so it won't let you do OLCI. I was complaining about this very issue with a lounge agent yesterday. The agent said sympathetically "When you have a reservation on two flights, the default is to do nothing" (which strikes me as applicable to many many other aspects of AC IT)
Ah, thanks. It checks out - I was upgraded for the second leg, and waitlisted on the first. This has not been the case in the past for me, though. Looks like a relatively new enhancement.
And yes, aerolotto worked (which for a 31 hour itinerary from initial check-in to bags out was a welcome development!)