How do I notify the system that a file in a CBFS Connect drive

If you, or some other third-party application, manually deletes a "file" from the backend storage that CBFS Connect is exposing as a virtual drive, and there is no way for either the OS or CBFS Connect to discover this fact on their own, then you need to inform them of this change explicitly using the NotifyDirectoryChange method. Refer to the documentation for more information.