The forum software has a bug. Every now and then, for no apparent reason, forums that should be hidden become visible. You can't access those forums, even though you can see they exist.
There are many forums here, not just the public ones you normally see. The Bakers have their own sections as well for their own uses. They are also hidden from us as you'd expect.
The forum software devs (3rd party) have been told about this many times and have not fixed it.
You wouldn't expect the Bakers to release new software without beta testing it first would you?