This occurs when the "voCollection" tag has not been set up correctly in the mod's data files. Worse, if they use the same tag as the base game scenery then they can turn those black too!

I explain in more detail here.
https://steamhost.cn/steamcommunity_com/workshop/discussions/18446744073709551615/2147595624110387769/?appid=600480

Firstly, in case anyone doesn't know what normals are: https://blender.stackexchange.com/questions/43462/why-do-normals-exist

Basically, 3D models which have "normals" data need to be kept separate to 3D models which don't have this data. They just need to have different "voCollection" tags. The tags can be literally anything e.g. "carrot" or "sponge". As long as "carrot" only contains 3D models which do have normal data and "sponge" only contains 3D models which do not have normal data.

The mod maker simply need to change the "voCollection" tag for the object causing the issue to something else. In the base game I make the "voCollection" tag for any models without normals to "{collection name}_no_normals" to make sure they are separate.

Hope that helps!

Thank you ! I will try to find what mod caused this

from what i know, a few of my scenery got issues with the tree from amazing mangroves, which once selected/placed will cause my scenery (like my rock borders) to go black, removing the tree and reloading the savegame will turn all black objects back, the modders are aware of this issue but it seems a fix is not easy