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Go into the Sib user's folder (/Users/yourusername/Library/Application Support/Avid/Sibelius, is hidden by default) and delete the "Playback Configurations" directory. Sibelius will generate a new one upon launch/restart. Create a new Configuration, see how it goes.
Go into the Sib user's folder (/Users/yourusername/Library/Application Support/Avid/Sibelius, is hidden by default) and delete the "Playback Configurations" directory. Sibelius will generate a new one upon launch/restart. Create a new Configuration, see how it goes.