I also discovered that apparently Windows 10 has a workaround for this issue, which is an option under
Language Settings/Administrative Language Settings/Change System Locale/Beta: Use Unicode UTF-8 for worldwide language support
Turning on this option (and restarting) magically makes even pre-existing executables accept Unicode text. I think it even fixes another SBCL/Unicode issue on Windows: https://bugs.launchpad.net/sbcl/+bug/1267540
Thanks for the fix, hoping to try it out later!
I also discovered that apparently Windows 10 has a workaround for this issue, which is an option under
Language Settings/ Administrative Language Settings/Change System Locale/Beta: Use Unicode UTF-8 for worldwide language support
Turning on this option (and restarting) magically makes even pre-existing executables accept Unicode text. I think it even fixes another SBCL/Unicode issue on Windows: https:/ /bugs.launchpad .net/sbcl/ +bug/1267540