Problem is caused by a beta feature in Windows 10 build 1803. To disable the offended beta feature:
- Start-Control Panel
- Select Region
- Click 'Change system locale' on the Administrative tab
- Uncheck 'Beta: Use Unicode UTF-8 for worldwide language support'
- Click Ok (will have to reboot)
Hopefully, this feature will be fixed before it is actually released. We can only hope :).