Launching mintstick from dmenu or rofi is not going to work because the application mintstick requires an option behind the command.

mintstick -m format
mintstick -m iso

That is the code it is waiting for.

If you use ALT + F3 you are using the menu of XFCE and behind the icon is the correct launch sequence.

That is how I launched Usb Image Writer.

But you can launch it from a terminal as well.