That usually indicates a slow connection or difficulty of the computer/browser to handle the data quickly. For reference, I almost never see it on my desktop Mac/ethernet, but often see it on my Chromebook/wifi. It can also happen when there is a problem with the shard your game is running on, or any kind of issue that affect connectivity in general (ISP problems, etc) It's almost always temporary, and shouldn't affect visibility of maps or characters. It's more likely to be an issue with your lighting setup. Some things to check: 1) what are your page settings? If you have turned on regular Fog of War, the default is completely obscured. You will need to manually clear areas for your character tokens to see. 2) Is there a light source on the page? Either the characters must emit light (such as a torch that anyone can see, or darkvision that only they can see) 3) Try turning off Advanced Fog of War. It is broken right now and leads to unexpected and unwanted results. 4) Probably doesn't need to be said, but I'm trying to be thorough: are the tokens you are placing for the characters on the same page that the player flag is on? 5) Test players' ability to see anything at all by putting their tokens on a test page that has no lighting or vision settings active at all. If they can see that, then the visibility problem is almost definitely one of the issues above.