You can't nest inline rolls, and you can't do /slash commands in inline rolls. So this is a limitation rather than a bug. If what you're trying to do is: [[floor((@{Valrok of Ol|AC}-10)/2)]], then rather than doing [[#test]], you would just do "#test" and hit enter, and it would work. Alternatively, you could define #test as just [floor((@{Valrok of Ol|AC}-10)/2) (without the brackets), and then you could do [[#test]] or /roll #test as needed.