System trigger group has vanished from Event Editor

I just realized that the System group of triggers has vanished from my current project. When I start a new project, it's present, but if I go back to my other application, the triggers available when I create a new event are only the ones for the sprites, boxes and mouse & keyboard. Copying a System trigger (say, Always) from a new app and pasting it into my other project works, but it doesn't bring back the System group when I try to make a new event or condition again.

I can easily transfer the work into a new app, but I'd like to know if there's a way to bring back the System group nonetheless. Thanks!

Actually, scratch that. I can't transfer the work into a new app, as whenever I try to copy a sprite from one app and paste it into a new one, all art for it vanishes, leaving it invisible.

Box objects don't seem to be affected.

I've heard a handful of reports of the system object disappearing, but I've never been able to reproduce it. Can you send the .cap that is doing this to ? Also, are you using families at all?

I've heard a handful of reports of the system object disappearing, but I've never been able to reproduce it. Can you send the .cap that is doing this to ? Also, are you using families at all?

I've sent you the .cap. Indeed, I'm using families in this app - could that be related to the problem?