Not sure what other programs you can drag an instance unto from the studio window to cause it to disappear like that. The object is still in studio, it just disappears from the view. I made it come back into the list by selecting it via script with the selection service.
Huh, that’s actually really weird because I tested dragging instances out into just the desktop to see if Studio just had a feature where dragging an instance off would just delete it, but it really is only with discord.