Very strange lightleak issue with outer walls

Hello all, I have one very strange lightleak, I now which object causes it but I can’t find a solution.

All my objects have great working custom made lightmaps, no overlaps, no leaks, every UV is aligned to the grid with the 1/lightmap res formula, more then 4 pixels gap between islands and everything builds fast

When I add my outer walls then this one causes leaks on objects that worked before. This room is the worse, it has leaks all over the place.

Can anyone please explain how this is possible?

u have to increase the light map setting to remove the leaking of light