When you are executing matlab in background on a server by screening the command you obviously cannot use the matlab interface. To disable it just use the -nodisplay option.
matlab -nodisplay -nosplash -r "download('$(LIST_)')"Be careful, dont even attempt to use the -nodesktop option because your screen command will never work. The explanation is in this post And this is an alternative to launch your screen in background
screen -A -m -d -S matlab matlab -nodisplay -nosplash