Pressing the Pause button ( || ) on the Silhouette machine (Portrait or CAMEO model) does not appear to take immediate action.
The Pause button may not immediately stop the job. The Pause button will only stop the job after it has completed the current continuous line it is working on. (i.e. If the Silhouette was cutting a series of circles, pressing the Pause button would not stop the cutting action until the Silhouette stopped cutting the circle it was working on when the button was pressed. It would then stop prior to moving over to complete further circles.)
As such, it may seem like the machine is not responding to the action of trying to pause.
The only immediate method to stop a cut job would be to power off the Silhouette completely. This will of course abandon the job rather than Pause. If powering off the Silhouette to stop the job, please note that the job cannot be resumed where it left off.