The Canvas support team has a link on a users profile that "clears the user's cache".
So far this has fixed issues when the items don't display on the course navigation or courses do not display in the Inbox to message. Recently we had several teachers who could not view the PEOPLE item in the course navigation and they could not view courses in the InBox when trying to send a message. We suspect several user issues can be resolved if we have access to this cache clearing tool.
We requested to have access to this magic tool as it clears the users Canvas cache which often is an issue. Let's vote it up that admins have access to it. I entered a ticket for our admin to have it but it was denied.
Support has a link on the profile as indicated below.