While I'm not an expert on this, I imagine this has to do with the way the file watcher works.
I suspect that a file watcher class talks with the operating system through some windows APIs that talk with the operating system disk I/O. When you save a file in windows, the file I/O notifies the "watchers". However, your networked file system is not controlled by (only accessible from) windows. So windows doesn't know about changes as they occur.