Matlab does not respond after setting DISPLAY=:0

I am trying to run Matlab in a HPC cluster environment. The job is submitted this way:

qsub -I -l select=1:ncpus=1:ngpus=1:gpu_model=v100,walltime=1:00:00

The underlying GPU is nVidia V100. Initially the DISPLAY variable is empty. After that, I type matlab to run it, matlab detected that there is no display so it selects software OpenGL rendering and starts as CLI. But if I quit matlab, type in the command line:

export DISPLAY=:0

and run matlab again, it does executes but displays nothing. I can still type in command in the terminal like quit, but matlab just does not respond to anything. Can you explain this phenomenon? What is happening to matlab? Thank you.

PS: The version of matlab is 2017a. The operating system is Linux and the node is intel x64.