Having the same issue.
Fatal error: [File:D:\Build\++UE4+Release-4.14+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\Templates\Casts.cpp] [Line: 11]
LogWindows:Error: Cast of LinkerPlaceholderExportObject /Game/1inventorySystem/Blueprints/BP_Crate.BP_Crate_C:Storage_GEN_VARIABLE.Storage_GEN_VARIABLE_BP_Storage_C_CAT to Actor failed
UATHelper: Packaging (Windows (32-bit)):