UDL not working

I'm running Dungeon of the Mad Mage, so there's always the possibility of the size of the maps causing the issue, but I spent the past 2 hours setting up the Dynamic Lighting for Floor 10 and found a slight issue. While in GM view, I can clearly see where the player tokens with Dark vision are able to see, but when a player enters, all they see is the token floating in the void, as if everything was dark. I know the dynamic lighting exists, as I have restricted movement on, so they can't move past a certain point, but this is just frustrating, after all my work. Any help is much appreciated. I use Chrome, and Windows, both up to date.

Just double-checking: is the player token set up to have sight? This is the most common problem, often occurring when sight is enabled but not saved as the default token and the character is later dragged from the journal, reverting to its original non-sighted settings.

Thanks for replying. Yes, the token does have its sight turned on, and it also has night vision (as the area we are in is dark).

Hmm, is the player using a supported browser (i.e. Chrome, Firefox), or might there be browser extensions causing problems? If they refresh the browser or log off/on does it correct itself? Sorry  don't have much more to try. Because of all the problems with UDL, I've just stuck with LDL and am avoiding all of the issues until UDL is ready for prime time.