Please launch the Console application (from the Utilities folder inside your Applications folder). It should open to All Messages, showing the log entries for everything that’s happened recently on your Mac. If you’ve previously narrowed the Console results, show the Log List and select All Messages before proceeding.
Switch back to Sketch, and try to trigger the issue you were experiencing. This will (hopefully!) print some output to the Console.
Return to Console and from the Menu Bar choose File › Save A Copy As… and attach the file to your report to aid in our investigation.
