Same issue here, it worked and now I just relaunched XCode and the same error message, failing to download..

The operation couldn’t be completed. (ModelCatalog.CatalogErrors.AssetErrors error 1.) Domain: ModelCatalog.CatalogErrors.AssetErrors Code: 1 User Info: { DVTErrorCreationDateKey = "2024-10-30 21:32:05 +0000"; } Failed to find asset: com.apple.fm.code.generate_small_v1.base - no asset Domain: ModelCatalog.CatalogErrors.AssetErrors Code: 1 System Information macOS Version 15.0.1 (Build 24A348) Xcode 16.1 (23503) (Build 16B40) Timestamp: 2024-10-30T17:32:05-04:00