but my site is not picking up the changes. I edited an article that has an interwiki link in it for the iw_prefix that I changed but when I preview/save that article, the link still refers to the old (iw_url) value.
If I add a new entry to the table, interwiki links using the new iw_prefix work and resolve to the iw_url of the new record. So I'm confident the table is being updated correctly.
Is there some interwiki caching going on that masks changes to existing rows in the table?