Backup-DbaDatabase -FileCount not Working

[B4MY]

Hello,

I made a Script for migrating Onprem DBs to Azure.
At the moment I stuck by creating Backup for an Database with Size over 200GB to an Azure Blob Storage:

WARNING: [14:36:01][Backup-DbaDatabase] Backup of [DB] failed | Microsoft.Data.SqlClient.SqlError: Write on "https://.blob.core.windows.net/1427.bak" failed: 1117(The request could not be performed because of an I/O device error.)

I read that Blob Storage only supports 200GB files.
https://techcommunity.microsoft.com/t5/azure-database-support-blog/lesson-learned-311-error-1117-the-request-could-not-be-performed/ba-p/3727337
So i tried to split the Backups in multiple Files.
But it is not working if i set the Filecount.
If i put in Switch -OutputScriptOnly i can see that the Query only returns one BackupFile

Backup-DbaDatabase -SqlInstance $SQLSource -AzureBaseUrl $Blobfolder -Type Full -EncryptionCertificate $BKPCert -EncryptionAlgorithm AES256 -CopyOnly -Database $Databasese.Name -FileCount 4 -CompressBackup -Verbose

did i something wrong ?

Thanks in advance
BAM