I've noticed some reproducible issues with seeing through walls. For the screenshots here I used DM preview, but these same things occur with players connect using normal LOS in a game (where I and the player's first noticed the issues). The screens are from the development campaign which I will zip up and send along with the unreleased map pack used to make the maps.
You can only see through the walls when a token is in specific squares. In this case to reproduce just drag a PC token from the combat tracker. When you move the token around after you can see through the wall, you will get FOW where the token could originally see through showing it can't see through in that square.
- The LOS01 series is from map 01a Dungeon, Room 01-07 Guardroom.
- The LOS11 series is from map 01b Dungeon, Room 01-10 Plank Room (next post).
In the LOS15 images I noticed something different. If you dragged the PC token from the combat tracker an placed it in the SE corner as shown you did not see through the wall initially as shown in 15a. But if you clicked the token again without moving it to unselect it, as shown in 15b and then clicked it again to select it as shown in 15c you could now see through the wall.