There is a known issue with channel routing when the SL3 is set to play at 44100 Hz on Mac computers. This is a driver issue.
If you experience incorrect channel routing with your SL3, go to Applications > Utilities > Audio MIDI setup and click on the SL3. Once highlighted, set the input sample rate to the default 48000 Hz and this should resolve the issue.
Contact the support team by opening a help request if this doesn't resolve the issue for you.