After Migrating a Scene to UE5.02 i have some Materials that are only Grey

Development Asset Creation
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After Migrating a Map from UE4.27 to UE5.02 i have some problems:

grey
grey1920×1053 398 KB

have some plants inside this Map an this Textures has color, but the materials are completely grey scale. Why? I can’t find the Reason for this?