I had everything running smoothly with Sonar Platinum, then I updated to the most recent version and I'm getting dropouts.  I noticed in the Performance module on the Control Bar that now only one of eight cpu cores is being used.  I reset the configuration file to default settings thinking that maybe something had changed in the code, but it still only uses one core.  I have Use Multi Processor engine checked in Preferences.  Can someone tell me what has changed, and how to get Sonar to use all the cpu cores?
Thanks.
 

If there is a problem, revert back to the previous installed version Sonar, that's the beauty of Command Center.   If you installed an early access version of Platinum, then just revert it back.  Remember, early access is NOT the completed version.
 
If it ain't broken, then don't fix it.

Try 22.6.0.26 that's the latest one, but it's an early access version. 
 
I had a problem and installed an early access version and if solved my Sonar crashing problem.
 
You can always roll back to what you were using originally.
 

Where would I find the early access files?  I usually just let command Center update it.

I found that changing the Enable Set ThreadIdealProcessor from True to False in the configuration file got Sonar to use more than one core.  I don't remember having to do that before. 

aspenleaf
I found that changing the Enable Set ThreadIdealProcessor from True to False in the configuration file got Sonar to use more than one core.  I don't remember having to do that before. 

I tried your change and still have 1 core instead of 4 in my case.

Did you have more than one core working before this update?  I did and don't know why it changed.  I noticed my buffer settings changed too.
I'm downloading the early access file now to see if it makes any difference.

I already have the early acces download installed. Only one core working.
 
Edit. 
What sample rate are you running? In 44.1 24 bit I have all four cores showing up, but with my last song samplerate 48 24 bit I only have 1 core showing up.
 

Try installing Park Control, to see if all your cores are unparked and available to Sonar.
 
https://bitsum.com/parkcontrol/
 

CowboyDan - I am at 24/96.  I also set the Mix ThreadCount to 8, because I have 8 cores.  I just installed the Early Access download and I have 8 cores working, but I haven't tested it yet.
 
davec69 - Yes, all of my cores are available.  Something changed all of my settings in the most recent official release.  I'm resetting everything as I remember which ones to change.  (I should write all of those settings down).