Under Tools->Monitor Sessions there is Contention tab. It refreshes everytime a different session is selected in the list of sessions above. So is this tab showing contention across the entire database ? or is it just showing for that session if that session is causing or experiencing any contention ?
If you look at the SQL under that page, you can see that WHERE clause limits the results to the active session from the main report - this is indicated with the :SID notation.