It appears to be problems with Yosemite:
http://community.wd.com/t5/WD-My-Cloud/os-X-yosemite-and-WD-my-cloud/m-p/829997#M25328
So put yourself in WD shoes for a moment. Both Apple and Microsoft are not easy partners to deal with. They can and do make changes to code. Given the fact that the vendor reps in this forum are vastly superior in reponsiveness than any other tech vendor I work with, when he said “they are working on it” they are working on it.
