Windows 10 Home 64-bit v1903 (build 18362.418)
Gpg4win 3.1.10

Steps to reproduce

1. Create a directory with unicode characters e.g. ThaiChar-ภาษาไทย
2. Create a simple text file inside that directory e.g. test.txt
3. Right-click the text file and select the Sign and encrypt menu

Result

A popup appeared

• Title: "GpgEX"
• Text: "Error returned by the GnuPG user interface (Kleopatra): No such file or directory"

Log file