You may want to check in and search through the dedicated EX2 subforum and the dedicated WD software subforum to see if there has been past discussion on your issue. For example here is one past discussion:
https://community.wd.com/t/wd-access-mac-does-not-recognize-me-2-nas-ex2-ex2-and-ultra/172008/
https://community.wd.com/c/network-attached-storage/wd-my-cloud-ex2
https://community.wd.com/c/wd-software-mobile-apps/wd-software
As always one troubleshooting step is to uninstall the software, then download the latest version and reinstall the software.
WD Access for Mac:
https://support.wdc.com/downloads.aspx?p=254
