Overview
When you define the default view in the Salesforce CRM Add-in, the user can navigate to and between child views or grouping levels of that view only.
The user cannot navigate to a view that is parent to the default view or go to the main view (the main vault level that shows up with the vault name).
Description
This behavior is by design and is a security measure that sandboxes the users in the area and content they need to see and work with only so they cannot go to other areas, views and content.
You can follow the release notes for an item with ID 162028 - this is an improvement that aims to remove the confusing behavior where users can see the parent view links, but they will not open (for example, either by hiding them, or by adding a configuration option for the behavior).
