I've just tried to use Roll20 where I have encountered a very strange bug. Some of my pages have turned white with the maps and several tokens becoming completely invisible. Alongside that any tokens I try to add are also invisible. I know they are on the correct layer, and while they can still be interacted with their Opacity is 100%. Additionally when I press Z I can still see the image files as normal. I have tried to duplicate the maps, change the proportions of the map, turned on and off Dynamic Lighting, used different browsers, etc. My players have experienced the same issues.