I think you should put a support ticket in.  You've made a good effort.  Time to let the support crew give you a hand.

I love the concept of a wireless mouse, and use a wireless keyboard, but hae never found a wireless mouse that would track accurately enough for my purposes.  They just always drove me crazy.
 
Just my two cents - I also agree with putting in a support ticket, just in case they have some kind of way to fix it for you.
 
Bob Bone
 

The reason is screen settings. Sonar doesn't support windows 125% and 150% settings.

Mystery solved! Not sure if Adq (above) is the tech that replied to an email I sent in, but yes, 
 
FROM TECH SUPPORT:
<<It sounds like your screen resolution or dpi may need to be increased on the problematic monitor. 
Please take a look at  and follow the instructions contained within and let me know if this makes any difference for you. Also be sure your screen resolution on both screens is at least 1280x800, the minimum resolution supported by SONAR.>>
 
My monitor resolutions are both 1920x1080 and I had increased the screen setting to 150% a long time ago -- okay, my eyes aren't the best, and that HD resolution can make things really tiny. So I set it to 100%, as the KB article suggests and the problem was solved. I bumped the screen up to 125% and it also seemed to work -- so a happy median for my eyes. 
 
Thanks to everyone who replied.

Billy86
Mystery solved! Not sure if Adq (above) is the tech that replied to an email I sent in, but yes, 
 
FROM TECH SUPPORT:
<<It sounds like your screen resolution or dpi may need to be increased on the problematic monitor. 
Please take a look at  and follow the instructions contained within and let me know if this makes any difference for you. Also be sure your screen resolution on both screens is at least 1280x800, the minimum resolution supported by SONAR.>>
 
My monitor resolutions are both 1920x1080 and I had increased the screen setting to 150% a long time ago -- okay, my eyes aren't the best, and that HD resolution can make things really tiny. So I set it to 100%, as the KB article suggests and the problem was solved. I bumped the screen up to 125% and it also seemed to work -- so a happy median for my eyes. 
 
Thanks to everyone who replied. 

 
Glad to hear you got it figured out Billy.  The moderators appreciate you editing the title of your post to add:[Solved]
That way people who might be looking for the same thing will know they can find an answer here.
 
Cheers!