It looks like in the RPG/ACG separation that was done recently /acgCharacters/{characterNumber} was broken. No matter which character you select, no sessions appear.
Is this an in progress thing or is it a bug?
It's a bug some of us have been seeing since mid-last week. RPG characters' links are working for me. Looking at Player Sessions, I can see the ACG reports, so it's not a complete loss of data.
I'm thinking that clicking the Sessions link for an ACG character is failing because ACG character names are currently considered NULL (which you can see when you look on the Player Sessions page).