Buddypress Forums Tab - "You do not have sufficient permission to access this page"

After struggling with Buddypress forums (sitewide/group forums) for some time, I finally decided to attempt a 100% clean reinstall.

My objective is to enable group forums.
I have:
- deleted all wp_bb tables in my DB
- deleted forum meta key from groups_groupmeta
- (manually) deleted all BBpress files on my server
- checked wp-config.php

In short, I've been pretty thorough.

Thought I'd do a clean reinstall, but now I cannot access the "Forums" tab in my Buddypress installation anymore.

How can I resolve this ?