Quick update; The lastest Mach3 download from Artsoft, v3.043.062, posted on their site contains the fix for Win 10 64bit 1803 (and beyond)! > http://www.machsupport.com/software/downloads-updates
You are welcome!
Future Microsoft updates are very unlikely to address the root-cause, therefore either the patch or the updated Mach3 download is needed for builds including/beyond 1803.
Happy CNCing everyone!
-Nathan & CNCRP team