If access to local storage in Windows is disabled, the navpane does not load.
The navpane shows a message saying loading over and over, and a message like Access denied appears in the browser console.
There may also be an error like this:
TypeError: Unable to get property 'getItem' of undefined or null reference
The navigation pane does not load, and continually displays the message Loading....
This can often be resolved by disabling protected mode or adding ServiceNow as a trusted site.