[_ck_]

If creating a new user and assigning them as a Keymaster works, then it’s obviously a problem where the user in the existing WP/WPMU table doesn’t have the correct role set by bbpress when it installs/configures itself.

For those that know what they are doing, you can examine the new, working admin user under phpmyadmin and compare them to the old non-working admin and see what’s different. I think roles are stored in the usermeta?

Unfortunately I personally don’t have the time/setup to try to hunt down the exact bug with this right now, but I bet there are plenty of people on those similar threads with experience who can tell you what’s wrong.

https://bbpress.org/forums/tags/wpmu

https://bbpress.org/forums/tags/keymaster

(also unfortunately this is yet another demonstration of bbpress integration weaknesses that must be fixed before it will be widely accepted by existing WP users. WP has a role editing table in the admin options, or might be a plugin, maybe that can be ported?)