I set up a few maps last month and tested things out using normal sized DL lines. I Re-Joined as a player and moved icons around. Collision worked great, there were no gaps in my walls, an everything went smoothly. Game day was yesterday, and suddenly players could freely move through the walls I had premade and tested. I quickly located the checkbox to restrict player movement which I had not seen before (is this new, or am I going crazy) but even with this enabled, a player can rub up next to a wall and se directly through it. I just tested again using the extra thick line, and it didn't make any difference and the player could still see straight through. Has there been an update recently that changed how player vision works with Dynamic Lightning?
