Some thoughts:
- Have you checked Apache if “Allow Override All” is enabled ( not commented out)?
- Where is your WP installed – at domain root or in subdirectory? If in subdirectory, the subdirectory name should not named the same as that of BP components – Groups, Members, Activity, Forums. If name of subdirectory is same , you would have to “rename” matching BP component name to something else in your wp-config.php file e.g. define ( 'BP_GROUPS_SLUG', 'sections' ); or if your subdirectory is named members, define ( 'BP_MEMBERS_SLUG', 'scouts' );