Customize View Button not Available when Viewing Entity Records

When users navigate to Lists > Relationships > Leads/Prospects/Customers, only Edit View button is available and the Customize View button is missing.

Possible reason for this is that the user is using a Custom View based on a Saved Search.

For Leads/Prospects/Customers > Set View = General and the List View page will auto refresh with the Customize View button instead of the Edit View button.