I had the same problem in Win 10. This removed the icon for me. Not elegant, and doesn't sort the root cause but it works.
- Right click an empty space on the desktop and select Display Settings from the menu.
- From the Settings menu select Multitasking.
- Scroll down to Virtual desktops.
- In the option "On the taskbar, show windows that are open on", select Only the desktop I am using.
The icon should disappear. This will cosmetically fix the issue until a new update.