This has finally been fixed. As suggested, it's because there are duplicate counties with the same name.
Due to external data-caching your map might not be up-to-date yet, but it will look like this: http://project-gc.com/images/ps_map.php?mapHash=c8de557922959db6171e9250aea52e50
We have in fact removed a few counties in their capital city, and replaced it with one big polygon.
Our polygon data for Ukraine is quite old and we would like to update it, and not the least, move it into our newer tech. It's hard for us to do anything with the old data we have, which is why we implemented a new system.
The problem with moving Ukraine to the new system is that some data seem to have been removed from OSM. We can not find Autonomous Republic of Crimea in the data for example.