For v4.x firmware single bay My Cloud units there is a database file (/var/local/autoMount/autoMount.db) that is maintained of USB devices that have been connected to the unit. There is some discussion of this database file (which can be accessed via SSH or using a stand alone SQL reader) in the following post/thread/discussion:
https://community.wd.com/t/my-cloud-cannot-not-mount-share-on-4tb-my-book/168409/12
One could try to rename the autoMount.db file, reboot their My Cloud then reattach the USB device to the My Cloud and see if that clears the 0K issue.
Since I don’t have a v2.x single bay My Cloud I don’t know if this same autoMount.db is located within that firmware and if so is it located at the same directory location.
