Player able to see entirety of map, even areas behind Dynamic Lighting lines

We had a problem this evening with one player being able to see the whole of the map: When I opened the Player View to see if I could see what they were seeing through there, it looked perfectly fine and as I'd expect it to look: The player was using Chrome. No-one else in the group was experiencing the problem. I asked the player to refresh their browser, but it made no difference. This is clearly quite a game-breaking type of bug!

Hi Styx! Several questions off the top of my head: 1. What browser are they using? Some unsupported browsers do not render Roll20 correctly. 2. Are they using any sort of extension that might block code execution? Some people have extensions or settings that block JavaScript for example, which would clobber dynamic lighting. 3. It might be that they have disabled or are bypassing WebGL for some reason. Have the player open get.webgl.org or webglreport.com. If WebGL or WebGL2 shows as unavailable or software-rendered, you might have found the problem. In Chrome, chrome://gpu gives more detail. Some other diagnostics: Have them try an incognito or private window (which typically disables all extensions) They can try a different supported browser (Chrom/Firefox) on the same machine. If DL works there, the cause is likely the original browser’s settings or extensions. If it fails in both, look at the drivers, the hardware, or the network. I'd hesitate before I call this a "bug". There aren't any widespread reports of such behavior. It's far more likely at this point that something is blocking proper execution on that local machine (since your View as Player shows proper behavior).

Try and reset the Explorer Mode. It looks to me like the player token has taken a tour of the map thus exposing the passages where they visited.