bbpress allows the creation of custom roles.
However the latest combination of WordPress and bbPress does not work if the code to do this is in the functions.php file of the child theme (or indeed parent theme!).
The code is shown in the bbpress documentation
If you put this code in a plugin, it seems to work fine.
Why does this not work
You can skip reading this if you just want the solution below !
bbpress uses WordPress roles and capabilities functionality.
WordPress loads both roles and capabilities as pages are rendered for the browser. These are created from code and database entries BUT held in a variable/variables for speed of execution.
My suspicion is that WordPress creates these variables after plugins have loaded, but before the child theme functions have executed, and therefore the filters are not executed correctly so don’t take effect.
I could spend days working out the solution, but the simple answer is below
My assumption is that as you are using code, you are comfortable in changing files and FTPing them to your site.
1. Install a plugin
This plugin is 3 lines long, so will not slow your site !!
a. Download this plugin using the link below
b. Go to Dashboard>plugins>add new
c. Click Upload, and select the file
d. Click install
e. and then activate
2. Download, amend and upload to your child theme a role-functions.php file
For a single file – download this file
Once downloaded, unzip and open the file and amend as desired – I use Notepadd ++ as my code editor – it is excellent, but any plaintext editor will work
Then FTP this file to your child theme so you end up with a file here
where %your-theme-name% is the name of your theme