Delete user preferences

Before you reset user preferences, be sure to first review your MainStage preferences and note non-default settings you've chosen. When resetting the MainStage 3 preferences, these preferences will return to default. For more information on preferences, see Preferences overview in the MainStage 3 User Guide. 

To reset your MainStage 3 user preference settings to their original state:

1. Quit MainStage 3 if it's open.
2. In the Finder, choose Go > Go to Folder from the menu.
3. Type: ~/Library/Preferences
4. Click the Go button.
5. Remove the com.apple.mainstage3.plist file from the Preferences folder.
6. Restart the computer.

Or, you can quit MainStage, open Terminal, then execute this command:

defaults delete com.apple.mainstage3

After reseting the preferences to default, see if the issue still happens. If it's fixed, set your preferences back to how you had them and test again.