I have a complicated problem with the module K2 Joomla.

Currently I am an old 1.5 site to update to Joomla 3.4. All 600 articles from the old site are neatly along migrated to 3.4 and K2 also runs on the latest version.

Many articles have been assigned to multiple categories and also all get along tags.

In the structure in which categories listed himself no items. But articles from other categories are also assigned to this.

So I installed the plugin "Additional Categories for K2" and all adjustment equalized as they are set in the old 1.5 site. For both categories for the menu.
However, I do not see any articles which are assigned to a second (blank) category.

I know there are dozens of possible settings, but like all such as are in the 1.5 site, why I see nothing.

Hello,

You need to address this issue to the extension's developer.