If one uses the forum search feature (magnifying glass icon upper right) they’ll see this is a common complaint with OS5. A few past discussions:
Per the following WD Support Knowledgebase Article for what is/isn’t supported on OS5.
My Cloud OS 5: Manage Files on Web and Mobile App
https://support-en.wd.com/app/answers/detail/a_id/29969
Important:
Managing content using the My Cloud OS 5 Client apps have the following limitations.
- Copy is not supported
- Moving content between shares is not supported
- Upload and Download of folders is not supported
- There is a 100 file download limitation for the My Cloud OS 5 Web/Mobile App.
For more details, please refer to My Cloud OS 5: WebApp Download Button Unavailable When Selecting More Than 100 Files
