I've got a Y-class fare on TK that's 4 segments long. I've got plenty of miles in my Aeroplan account. I've managed to easily upgrade 3 of the 4 segments from Economy to Business class using miles from the Aeroplan.com web tool. Unfortunately the fourth segment is giving me trouble for some reason. I'm getting a fairly clear, "inventory not available" message from the Aeroplan tool.

My ExpertFlyer account shows "4" available in J-class for all my segments (I think that's the max they'll show for some reason, because my first three segments showed 4 available both before and after I did my upgrade, which consumed 2 seats).

So my question is; how accurate is ExpertFlyer with this kind of inventory? I've checked multiple times over the course of about 36 hours. Is it a glitch?