The most common reason why Professional Service Providers are unable to load a SideDrawer is because their client has changed the permission settings.

While, by default, Professional Service Providers are granted full access to SideDrawers they sponsor, a client has the ability to restrict any collaborator's access.

If your client has restricted your access you'll need to reach out to them to have them change it. And be sure to send them this link on how to change permission settings to help them out.