Attempting to encrypt a file with an umlaut in its name using the GpgEX context menu results in the following error message:

GpgEX
Fehlermeldung der GnuPG Benutzerschnittstelle (Kleopatra):
No such file or directory

Depending on the MS Windows configuration, it is easier to use emojis in the file name to enforce the use of wide characters for testing purposes.