Thanks for the response.
I’m currently excluding the sideblog posts by using !is_category(), but since they are still being included in the default query_posts() I’m getting less than my desired (8) posts per page. I appreciate the explaination though.
Upon further investigation, I find my host is using 4.0.23. I guess I’ll keep an eye open for any fixes, and in the meantime I’ll just make them single-category.
