This is an ongoing problem. http://community.wd.com/t5/WD-My-Cloud/Dashboard-problem-No-info-in-Capacity-usage/td-p/729452
For a full explanation check this post http://community.wd.com/t5/WD-My-Cloud/before-you-pack-up-your-WD-and-return-it-let-s-talk-about/td-p/683307
Scroll down to the heading “Finally the problem with WD Cloud” there you will find some suggestions for a fix.
Also check this for more details. http://community.wd.com/t5/WD-My-Cloud/Hidden-wdmc-directories-created-by-mcserver-and-photodbmerger/m-p/682091/highlight/true#M7765
