A Problem after Windows Update?
Windows 10 has a major update every half year.
After the Windows Update, some user encountered a strange behavior of JoyToKey, such as the disappearance of JoyToKey icon on the task bar.
If you encounter such issues, please “Restart” Windows once to see if it helps. (Note: “Restart” of Windows cleanly kills and restart all system softwares, while “Shutdown” does not)