I am using the vanila assets , the ones with problems are the mountain big stuff , they look fine inthe CK , but ingame show no snow ... is it may be something related to climate or what?
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MountainCliff01_HeavySN
MountainCliff02_HeavySN
MountainRidge01_Heavy_SN
MountainRidge02_Heavy_SN
Put some of the objects you mentioned in my test worldspace and they did show up with snow. At first I had climate set to 'none', then I tried 'SkyrimClimate'. Both worked, so I doubt it has anything to do with climate. No idea what's wrong. Do you have any mods installed that alter the way snow works? Maybe the mod that gives snow a texture? No idea why it should affect custom worldspaces, but since it definitely works in my game I can only assume that in your game something is different than in my game (and that has to be a mod).