WPforo settings: Replace Author Link to Forum Profile and Replace Author Link to Forum Profile are set to yes. If both are set to no then the bug goes away but obviously the view link is now set "author" so will return a 404.

Affects the view user links from Dashboard/Users when a member has registered with a username that starts with numbers, for example, 45express. In WP/Users, clicking on the view link will return one of two results; either the link will go to the homepage or, the link will go to a different user whose user_id is 45.