The issue is that the submenu links have a problem. The previous default submenu still points to /members/username/activity/ and not to /members/username/activity/just-me/ as it now should. This causes a mixup problem between the new and previous default subnav. Any ideas?
I found out that the Group component class gives you the opportunity to override the default ‘home’ subnav either by using the BP_GROUPS_DEFAULT_EXTENSION constant or by using the bp_groups_default_extension filter.
I could not find anything like this for the Activity component.