Problems with VNC server usage for a headless system

After starting VNC server, executing the simplest environment initialization script,

import minerl
import gym
env = gym.make('MineRLNavigateDense-v0')

while specifying DISPLAY, in the following way

DISPLAY=:<vnc#> python

still results in an error, regarding the inability to detect X server, monitor, etc.
In contrast, launching xclock with the same DISPLAY specification works perfectly.
What steps should I take in order to try and resolve this issue?

Thanks for the details you provided - would you mind making am issue on github to track this? @william_guss may have some insight, if you could include your log file and the exact error that would help us resolve this for you!