You show the link but no img elements for avatars at all.
You need to provide details of your setup, but also run some simple tests, is this a media upload issue, does your WP install correctly handle media (likely not the issue as one would expect default avatars) Is this a plugin issue? de-activate all but BP plugin establish if some other plugin is causing an issue. Activate one of the stock WP themes to establish if avatars show then if they do we have a theme issue.
I tested the theme on a vanilla install and it works perfectly out of the box.
You probably omitted a setting or use a conflictual plugin. Or did you some custom work ? Anyway…
See first default avatar in WP
dashboard > Settings > Discussion
Check mystery man
Save !
Go to permalinks and activate pretty permalinks. Save !
Go to BuddyPres settings and verify anything.
Deactivate all other plugins except BP and see if you got it to work.
