Greetings imocha,
Sorry to hear about your smart group creation issue! I can’t see your screenshot, but do you happen to be using EndNote X8 on a Mac running macOS High Sierra? If so, this is a known issue that our developers are aware of. For now, after EndNote’s crashes once the smart group is created, I’d recommend relaunching EndNote to see your library with the newly-created smart group. Please let me know if this works for you. Once again, I do apologize for any inconvenience caused by this situation.