We tried and received nothing. Because we booked the cruise on board, we got a better rate. In order to get the grats included, we would have to pay the higher rate.
Just ask the other cruisers in the area if anyone is using the chair. They will tell you when someone was last there, if at all. Unless they are the ones saving it.
On our last cruise, bars were closed between 11 and midnight. Way too early for us. We would have to get extra drinks at last call to have after close. It would be easier if we brought our own, for after hours.
We were just there this week, and were worried we wouldn't get one as they all seemed to be occupied. We did get one, but they were all open and set up with nobody checking. We believe that some were being used without a ticket.