Back to exit rows - in my experience, it seems that half of the time you can get your exit row 24hrs before flight on OLCI, and the other half of the time they remain blocked until physical airport check in.
I then ask at the desk for an exit row, and often I am assured that there are other passengers in the exit rows. More often than not, when I go to the lounge and ask the same question, they will make the call and open up the exit seat that has been previously "booked".
My only advice is to keep on asking!