Active users, doesn´t cleanup every 10 min.

Not seen this issue. Active Users are held in Application Variables and not the database even if you have session held in the database.

To fire the function that clears out the active users list you need to have active users to fire the function.

Search robots can be active for many hours and if you are using multiple web wiz forums on the same domain unless you change the application variable prefix for each forum they can interfere with each other causing strange results.

As HTTP is a stateless protocol and the connection is dropped as soon as the page is loaded the active users is a best effort rather than 100% accurate so should be seen as a guide only.