Same problem here, AutoCAD Civil 3D 2018... Also, it doesn't just effect pinned icons for me, it affects any icon emblems that are there for open programs... Anyone find a fix yet?
Having a similar problem with Outlook occasionally spawning numerous open versions just by clicking on the Outlook icon in the task bar. Most often happens when trying to insert a picture but can happen at other odd times. I use a CAD problem called Altium which has also seen problems occurring for about the last six months. Latest Parallels with the latest Windows 10 or Windows 8.
I followed the instructions turning off the "Auto detect for games" option and haven't had a problem since....
I'll keep you posted if the problems recur.