Here are links to MS Answers Forum Post and Nokia Support forum for this topic. The following is a procedure that worked for me based on answers from the two forums.
Can't post status updates to Facebook via Me Tile or Facebook - Microsoft Answers
Nokia Support Discussions - Re: Can't post status updates to Facebook via Me T... - Nokia Support Discussions
This worked for me once I finally got the app to show up so I could modify settings. I found that because I have secure browsing enabled that it would not show up for me. So I've added a couple steps to your list (in the event anyone else has secure browsing enabled).
1. Facebook - Account Settings - Security - Secure Browsing - Set to 'Disable'
2. Go to the 'Windows Phone' App in Facebook - enter it in the search box. Note - Go to the app, not the group.
3. Refresh several times - Ctrl+F5
4. Go to Facebook Home
5. Windows Phone should be there under 'Apps'
5.1. If it doesn't show up go back to the 'Windows Phone' app (Step 2) and refresh several more times. If the page appears to be 'loading' allow it some time to do so. Nothing ever actually appeared on the page for me but the time it finally worked it did sit and act like it was attempting to load something for an extended period of time.
6. Click on the pencil icon next to it and select 'Edit Settings'
7. Set up your wall post viewing rights the way you want them.
… all I had to do was modify mine and it immediately worked. I even changed it back to the original custom settings and it still worked after. It's almost as if it somehow null'd out those settings and just needed them reset.
8. Save the settings
… test posting a message or checking in from the 'Me' tile and if good proceed.
9. Facebook - Account Settings - Security - Secure Browsing - Set to 'Enable'
… even after settings secure browsing back to an on state I'm still in good shape!
I now feel like a big piece of my WP Experience is back and that makes me a happy WP Enthusiast once again!