The problem single bay/single drive My Cloud users face is their products are either at End of Software Support status (first gen v4.x) or approaching it with “limited updates” (second gen v2.x). So if Apple (or Microsoft) changes things that breaks access, its possible WD will not fix the issue if the My Cloud itself is the issue.
One could attempt to change from AFP to SMB and see if Time Machine will start working again. See the following post in another discussion on Time Machine Issues.
Or one could use a third party backup program that works on Mac’s and supports backing up to local network NAS devices.
