Cant see thumbnails + errors

hii, I havent used this app for a few years and had to redownload, I cant see thumbnails for anything and get an error message while opening them. (I am in create 3d mesh CAS) as far as i know i have no anti virus programs
Here is the error message The Sims 4 Studio - Version 3.1.5.8

System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.

at S4Studio.Core.CloneEngine.CloneCatalogResource[T](IResourceProvider game_files, IStringTableCache global_stbl, IDBPFPackage result, UInt64 instance, String hash_salt, CloneRenumberOption renumber_option, Boolean include_variant_thumb, Settings settings)

at S4Studio.ViewModels.CAS.CASPrototype.Clone(IDBPFPackage p, CloneRenumberOption create_cas_option, String hash_salt)

at S4Studio.Shared.CASFeatureViewModel.Clone(IDBPFPackage package, String hash, IEnumerable`1 selected_prototypes)

at S4Studio.Shared.FeatureViewModel.<>c__DisplayClass28_0.<CreateItem>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()

--- End of inner exception stack trace ---

---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.

at S4Studio.Core.CloneEngine.CloneCatalogResource[T](IResourceProvider game_files, IStringTableCache global_stbl, IDBPFPackage result, UInt64 instance, String hash_salt, CloneRenumberOption renumber_option, Boolean include_variant_thumb, Settings settings)

at S4Studio.ViewModels.CAS.CASPrototype.Clone(IDBPFPackage p, CloneRenumberOption create_cas_option, String hash_salt)

at S4Studio.Shared.CASFeatureViewModel.Clone(IDBPFPackage package, String hash, IEnumerable`1 selected_prototypes)

at S4Studio.Shared.FeatureViewModel.<>c__DisplayClass28_0.<CreateItem>b__0()

at System.Threading.Tasks.Task.InnerInvoke()

at System.Threading.Tasks.Task.Execute()<---