Player tokens able to see through Line of Sight walls

[Ecks]

Ran into this issue on a map from the Tomb of Annihilation module, where players could move up to a wall and see through it and other wall occluders. Even adding additional wall occluders did not block their line of sight. Note the screenshots include possible spoilers for the Tomb of Annihilation adventure (I tried to keep the screenshots small).

To recreate in a new 5E campaign, no extensions:

1. Load the Tomb of Annihilation module
2. Create a PC, assign token, add to CT tracker
3. Open the map "Player Map - Vault of Reflection", turn Player Vision Preview on
4. Either give the token an effect to provide lighting or disable lighting, either works
5. Add the PC token to the map in Area 39, then move it to the location shown via dragging with mouse (upwards towards the wall): Capture1.jpg
6. Token can see through multiple layers of walls (kept screenshot smaller than impacted area to avoid spoilers), and adding new walls to block their line of sight has no effect: Capture2.jpg

I used Player Vision Preview above but you'll see the same thing if you connect with a player client - the player token can see through this wall and multiple additional layers of walls (almost clear across the map). One other observation is the occluders the player token can see through all appear to be in the same "set" as the wall they are intersecting. It also looks like the token might be directly centered on the wall segment, potentially placing the "center" of the token within the wall occluder line which might explain why they can see through walls. Though, when I added another segment to block their vision (in Capture2.jpg) it didn't block vision even though it was a separate occluder segment.

I don't think the issue is necessarily restricted to just this location (or just this map). This happened in another area on this map as well.

FGU v4.1.2
5E ruleset v2021-07-06
Windows 10

[Zacchaeus]

Looks like that might have to do with the relative position of the grid and the occluder just at that point. If I redraw the wall just a smidgeon further back the token no longer goes through the wall far enough to see the other side of the wall.

[Ecks]

Yeah, I noticed that as well. It looked like the grid and wall occluder might overlay just right so that when the token is snapped to a half-grid space the center point of the token falls directly on the wall. If this is the case, perhaps the token could be considered on neither side of the wall for vision purposes to avoid any potential spoilers (i.e. they see nothing instead of both sides).

Though, it seems there may be something else going on with this particular example, because the token gains visibility through multiple layers of walls instead of just the intersecting wall.

[Shapeshifter1923]

We experienced this and it turned out that I had added some line of sight, on the fly, after I had placed a players token on the map, that player alone was able to see through the newly added LOS. Problem solved by removing said player token then re-adding from the Combat Tracker

[Ecks]

Version 4.1.13 (2022-01)

• Image grid-snapped token movement could sometimes end up inside LoS blockers which were also grid-snapped. Fixed.

Not sure if this fix in the 4.1.13 update should have addressed this issue, but it still happens on this map with the latest updates (same steps to recreate in OP).

[Moon Wizard]

The fix was only for movement, not visibility.

Regards,
JPG

[ddavison]

Hello Ecks,

I'm reviewing older tickets to see if they are still a problem and I cannot currently reproduce this issue with that map and the set of steps you posted. We have had a lot of updates to this so far, can you let me know if you still see the issue?

[Ecks]

I haven't seen this one recently - I think it was fixed in an update at some point. Thanks for checking!