While there were some glitches with the very first preview of Apple's new macOS, StitchBuddy is now working flawlessly, without any update required. I tested not only the main application, but its Quick Look and Spotlight plugins, and all Automator actions.

The only hick-up I found is a confirmation required in Automator when using 3rd-party actions … without authorization by the user an action cannot be added to any workflow. Unfortunately the confirmation window is only shown when clicking on an action, not when directly dragging it. But hey, macOS is still in beta phase and things might change until it will be published … for better or for worse.