Discover Mycloud not syncing for some weeks. Chose to back up all files and format. Reinstalled WD Sync, three days later found still not working correctly. Now discovered that when it decides to ‘hang’ pause and restart will sync next directory then it stops again. Pause and restart repeatedly works but who wants to spend days doing this.
WD Sync is what it is. More than a few people have problems with it. The following WD Support Knowledge Base articles may be relevent to your issue.
If you do not need remote syncing, where a computer is in a remote location and syncs to the My Cloud, one can use third party sync software rather than WD Sync. Note that most third party sync software will generally only sync to a local networked My Cloud. Free File Sync (http://freefilesync.org/) is one such free third party program some have turned to rather than using WD Sync.