The current 64bit version of M-Tron Pro works OK for me in the current SONAR on Win10. Are you using the 64bit version of the plug-in?

good question scook. Just looked at plug file which is in my program files directory (not the x86 directory). It is:
 
M-Tron Pro.dll and according to properties is ver 1.0.0.35, date modified is 8/12/2008. Need to look into this further. Glad to know it's working for you. That gives me hope.

I am running 2.1.0.0 modified 18 Jan 2013
If you are running a 32bit version, SONAR will tell you by adding (32-bit) to the plug-in name in all the plug-in lists. Also the plug-in is shown in green in the browser. By default, 32bit plug-ins loaded by BitBridge do not display the standard VST header.

ok, so looks like i've got 64 bit but obviously outdated. thanks!!