There’s only one way to solve this problem if your audio interface has more than one output.
Create another output in the mixer, and, for example, send layers to 1-2 as the main output, and send the stacks or backing track to the newly created output 3-4 (on your audio card). This was the only way I was able to eliminate the crackling noise when the multiprocessor function was enabled in the settings.
Here is a link, this issue has already been raised but it has not been resolved.