Migrate classic storage accounts to ARM, resource name is Storage accounts (classic), but type is microsoft.storage/storageaccounts

Question

I am trying to migrate our classic storage account to ARM. However, there is no Migration to ARM button under the setting section for our Storage Account. So, I try to use PowerShell command, however when running the Move-AzureStorageAccount -Validate -StorageAccountName command, the validation failed saying that the storage account that I provided was not found. Yet, when running the Get-AzStorageAccount function the same storage account does exist. It seems like the storage account that I provided is not classic, yet the resource name does contain classic but the types are not  **microsoft.classicstorage/storageaccounts**. So, are those storage accounts "classic"? If so, how do I proceed with the migration? Since both portal and PowerShell does not work in this case.