a new lightmass artifact

hey. a lightmass artifact again:
perhaps you know. every now and then i stumble into these kind of baking problems.
happens only right below the ceilings and getting smaller when reaching the corners.
high baking qualities make the sawteeth smaller, lower qulities make them larger. it is not lightmap size dependent.
all rooms where i witnessed this for now had spotlights in them, like you see in the picture.
do you know these effects and know why they happen?

​​​​​​​i cannot find any other thread or post on teh interwebs that discussed this error before. i am clueless :frowning:

yes thank you. i also have this in production builds with 0.1 scale and 10 quality. and the geometry doesn’t extend beyond the ceiling. this is the actual geometry you see there. the red selected polygon is the ceiling