Your line numbers do not match up with v2.9’s, which is why I recommend re-installing. Not sure how re-installing will cause problems unless you have directly modified core files in the past.
Regarding bp-custom.php, a quick search on Google would have explained what to do with it. Regardless, here’s the link to find out more:
bp-custom.php
If the code snippet I provided didn’t work in your theme’s functions.php, it most likely will not work in bp-custom.php either.
The other potential issue is there might be a plugin conflict.
