[BUG] Site category selector with no selection on all sites

I have 3 sites planned to add in a "Official" category. After adding 3 of them into the category, I hide the category for no one who can select (its "official"). I went to one of the sites above and found no description entered. Meanwhile, the selector had already changed to "No selection" but I have checked its still under the category on "Site Category Listing".
I typed in the description of the site for category listing. After I press "Save", and I found out all the sites (including other 2) are unable to change the Site Category, even the 4th one without any selection before that.

I have already tried to deactivate the plugin and re-active it, even re-install the plugin with no luck.
Support access is grant for your help.