Either OS X updates or WMDCloud updates and the time machine backup stops working because of something - sparse bundle or as of now, just no drive appearing in the TM backup options window.
Im currently on Yosemite 10.10.5 with an all but new MBP and the MyCloud drive is updated to v04.04.01-112
If I navigate to the backup partition on the drive, its empty where previously it would show a backup with date, that you could access?
The drive is connected to the main router and does everything its meant to perfectly with the exception of backing up which was its primary purpose.
The myCloud drive appears as it should on the desktop with all the correct partitions. It appears correctly in the WD My Cloud window as it should, everything shows correctly and in the settings area, General - Mac Backups is set ON and the drive shows correctly.
I have only the AFP checked in sharing options - so thats as it should be.
When you navigate to the drive you can no longer see the backup files - which you could always do before, I never needed to really use TimeMachine - I could simply navigate to a given date and pickup the file from the backup collection.
When I go to the time machine backups nothing appears, despite the backup partition being mounted on the desktop.