Forum taxonomy menu not populated at node/add/forum

Repeatable: Always

Steps to repeat:

1. download and unzip og_forum from  http://ftp.drupal.org/files/projects/og_forum-6.x-2.0.tar.gz into the modules folder.
2. Setup forum structure and Organic Forum settings as described below
3. goto URL node/add/forum

Expected results:

The forum dropdown list populated with the forums the user have access to post to.

Actual results:

The forum dropdown list is empty ("please select" being the only entry). It is not possible to add new forum topic.

Related threads:

Forum taxonomy menu not populated when creating new node

Further details:

After updating OG forum to the latest version (6.x.2.0) it is no longer possible to add new forum topics via the URL node/add/forum, since the forum taxonomy dropdown is not populated , neither as anonymous, authenticated user or user 1.

If I make forum topics as a group member into the OG forum -  node/add/forum/83?gids[]=147 - the dropdown is populated with the OG forums. 

If I deactivete OG forum everything works as it should (except of course now the former OG forum appears in the forum list for all users).

We have the following forum structure - admin/content/forum:

• Public forum container 1
  • Public forum a
  • Public forum b
• Public forum container 2
  • Public forum c
  • Public forum d
  • ...
• OG Forum container
  • OG forum a
  • OG forum b
  • ...

Settings:

Organic groups access configuration admin/og/og_access >

• Visibility of posts : Visible only within the targeted groups.

Private groups

• New group home pages and default audience are always private.

OG forum admin/og/og_forum > group forum container >

• Would you like all group forums to be placed in the same container? : checked
• Forum publicity administration: nothing checked

Content type forum - admin/content/node-type/forum >

• Organic groups settings: May not be posted into a group (I also tried "Standard group post (typically only author may edit)").

Hope someone can clarify what has gone wrong. The error happened after a lot of modules being updated + Drupal core updated to 6.14 - so other things might play a role!