When I changed my category slugs I still see all the old posts on the category listing page at the new URL, but the feeds are empty except for the few posts I've published since the slug changes.
Category: "Cat One" slug changed from "cat-one" to "cat_one"
/category/cat-one/ now 404s, good
/category/cat_one/ shows all posts formerly visible at above URL, good
/category/cat_one/feed/ shows no post entries! VERY BAD!
With a little snooping I found the new slugs stored in the wp_terms table but the category_nicename column in the wp_category table still had the old slugs. Is this an issue anyone else has seen?