I spent several days now trying to fix the seams in my unity scene whenever I hit the lightbaking button.

My setup is a wall out of different parts created in blender and then stitched together in unity.

I already tried to change every single setting in the Lighting>Scene window. Nothing seams to fix the problem -> after baking there are light seams between the wall parts and when I zoom out the seams are dark/black. See screenshots, they probably explain best.