Start by seeing the dedicated subforum for the My Cloud EX2 where users more familiar with that device may be assist. This subforum (My Cloud) typically deals with the single bay/single drive My Cloud model.
As a troubleshooting step, disable Cloud Access/Remote Access in the My Cloud Dashboard > Settings. Wait a few minutes. Then re-enable the Cloud Access/Remote Access.
Make sure to check the settings for the user in the Cloud Access tab page. Because the MyCloud.com web portal uses a separate/different set of login information, make sure (if you haven’t already done so) to use the correct login information that is tied to a My Cloud Dashboard account that has access to the Private Shares.