@IG-88, I'm really sorry about this but for whatever reason the config of the VM did not contain the passthrough of the USB controller anymore. Also older backups did not contain it. So I've added it again and voilà the USB drives are recognized!
Really have no idea how this could have happened and why the backups to the USB drives could have happened.
But I've learned how to recover an array through a live linux, so thanks for that! And for your patience!
