Bug? Player got a white screen then the entire map was revealed (I'm using dynamic lighting on a map I created)

Just had a session where one of my players had his screen white-out then the entire map was revealed for him - including unexplored / hidden areas. Map stayed revealed for him until the entire group logged out & I restarted the session. Is this a known issue (& if so is there a way to stop it happening again as it revealed a few in-game surprises prematurely)

If you're using the Updated DL, read and psot in the main feedback thread for it, someone else might have encountered it. <a href="https://app.roll20.net/forum/post/9072910/updated-dynamic-lighting-feedback-thread" rel="nofollow">https://app.roll20.net/forum/post/9072910/updated-dynamic-lighting-feedback-thread</a> This post have nothing to do with "Character Sheets &amp; Compendium" , so would have been better fit to post in either the "Questions and Macros" or the "Bugs &amp; Reports" sub forums.