Hello Alex,

when there are no menu items linking to some K2 contents the alias can't be resolved by the Joomla SEF routing and the string 'component/k2' can't be replaced.

As my suggestion would be exclude those K2 categories from the sitemap, eventually keeping contents from nested subcategories.

To exclude specific K2 categories you can use a 'where' condition and the list of categories id to exclude comma separated, you can have a look at this post where it's already been explained: http://storejextensions.org/forum/view/10-jsitemap/1301-exclude-single-k2-item.html

John