Just thought id share a little something i come accross today.
In the main web console i can see Notification Triggers that are defined in libraries that i have created under the devices particualr sensor. (in my case a librabry trigger i set up for PING)
The library triggers do not show in the PRTG Desktop when looking at the same devices sensor - just shows a blank box.
I know the Desktop is still in Beta, but just sharing my experience.