Lightmassbaking Dont get rid of artifacts even with high settings

Hello, I am having a lot of problems to get rid of black artifacts on Borders or sharp edges. I am using the highest settings for baking and have rediculus high Lightmap resolutions. But still the black artifacts apear in certain areas. Any ideas how to solve that?
Here is some screenshots from a stair. You can see the Lightmap desity is high and the UVs look good to me. Any Ideas?

Sure. Here are the settings. I baked with Production Quality.