If one uses the forum search feature, magnifying glass icon upper right, they’d find that there is NO answer from WD on when, or even if, WD Sync will be fixed to work with High Sierra in the past discussions on this issue.
The workaround if one isn’t syncing to a remote My Cloud is to use a third party sync program to sync to a local My Cloud device. Free File Sync (https://www.freefilesync.org/) is one such free sync program others here use for syncing to a local My Cloud.
