gswitz
I will say, that when you normalize huge audio, cancelling can take a LOOOOOONG time.
I find myself canceling for what ever reason often enough to know that you have to wait for it to stop. Just click it once and wait. Like gswitz says, if it's a lot of info that you are bounceing, it could take a LONG time. So just sit back and stare!
There is no indication that Sonar has received your command and is in the process of "canceling." I thought if sending in a feature request about this at one time.