findOrphanFiles, findOrphanDescriptors <not supported>

I am using the built-in Amazon S3 implementation on platform version 6.10.10. When using the app-core.cuba:type=FileStorage bean, the findOrphanFiles() and findOrphanDescriptors() only return a string <not supported>. Why would this be happening? Could it be permissions with our S3 account?

Seems like it is simply not supported for any custom implementation of FileStorage: