BuddyPress.org

1. you aren’t supposed to do anything with the do_action. I was just showing you that hook exists.

2 & 3 – did you put the function in BOTH functions.php and bp-custom.php ?
If so, I said OR not AND. In both places it will cause a fatal error and show an entry in the log.
Learn how to debug in WP: https://codex.wordpress.org/WP_DEBUG

If not, then I don’t know what the issue is. It works properly on my test install.