It could be a theme or plugin issue
Plugins
Deactivate all but bbpress and see if this fixes. if it does, re-enable one at a time to see which is causing the error.
Themes
If plugins don’t pinpoint the problem, as a test switch to a default theme such as twentytwelve, and see if this fixes.
I had the exact same issue. Switching to a basic theme didn’t work but deactivating all plugins did. However, after re-activating them all one-by-one the issue hasn’t re-appeared and the Forum options are still there.
If it helps anyone get to the bottom of this issue, when I first activated the plugin and tried to direct me to the welcome page I, instead, go a message along the line of “Insufficient permissions” which was odd. I’m guessing it was then a permissions issue that prevented the menu options from then appearing in admin.
Thanks Dartiss it worked when i have deactivated all plugins.
@seojobb – so now you ned to work out which one is causing the conflict by re-enabling one at a time
No, has happened again – menus have disappeared. As I mentioned previously, re-activating all plugins and it works again, so cannot narrow down the cause.
hmm, it must be on doing something with one of the plugins – like looking at the settings page of the plugin.