I just got Sonar Platinum (late bloomer, sorry...) a few days ago and was trying to make some test projects to get to know the program. When I was recording MIDI tracks, instead of hearing the metronome tick off after I set it, I would hear a buzzing noise (like the metronome wav file short-looping onto itself). To stop the buzzing noise, I would have to stop the recording.
This would be an intermittent problem, probably happening 50-60% of the time. Otherwise, the count-off would go normally. 
 
Anyone know what's causing this?

Sounds like an audio clock/driver issue. Make sure SONAR is set to use ASIO driver mode in Preferences > Audio playback and Recording, and is not set to Share Drivers. Then under Driver Settings, make sure that channels of the Scarlett are selected as Playback and Record Timing Masters.
 
And if you've installed ASIO4ALL for any reason, you should uninstall it, and use the Scarlett's native ASIO driver.

brundlefly
Sounds like an audio clock/driver issue. Make sure SONAR is set to use ASIO driver mode in Preferences > Audio playback and Recording, and is not set to Share Drivers. Then under Driver Settings, make sure that channels of the Scarlett are selected as Playback and Record Timing Masters.
 
And if you've installed ASIO4ALL for any reason, you should uninstall it, and use the Scarlett's native ASIO driver.

As far as I know, everything was already set to exactly what you've described, and I never installed ASIO4ALL. I will double-check though. I also have the latest version of the Scarlett drivers.

Hi. Just curious. Do you use MIDI or Audio Metronome? And where is the Metronome routed to?
All the best.