I'm not sure what's the exact mechanics behind this, but commit list seems to be cached in a way which makes most recent commits invisible in certain situations.
Basic steps to see this problem: click any commit number to see the commit changes -> go back with the browser to the commit list -> recent commits are gone from the list, sometimes even the one that you just saw on it's details page.
In my case refreshing bitbucket cache (ctrl + f5 on windows) on commit list helps getting newest commits to the cache, so I can navigate history to the list and see every commit. When I specifically click on 'commits' tab, recent commits are visible too, so that's good. But as soon as I navigate via browser history to commits and there are some new ones, I don't see them.