if you encounter problem while running Unetbootin, that an error will prompt you to run a piece of code. Run the code in su(sudo should work too), because it worked for me. This happens when you install Unetbootin from distribution's package. Compiling would work fine?
dnf install unetbootin
su -c 'QT_X11_NO_MITSHM=1 /usr/bin/unetbootin'
sudo 'QX_X11_NO_MITSHM=1 /usr/bin/unetbootin'