I am beginning to regret my pretty permalinks. Apparently it broke the RSS feed for some subscribers. The problem was caused by a combination of factors. When I started this blog, I used a different blog engine; and when I migrated to WordPress I fixed it so that the old feed URL still worked. Moving to pretty permalinks broke that feed, although the normal WordPress feeds still worked. There was no error; the feed was just empty. The reason it broke is … something to do with redirects. Fixed now.
Apologies if this affected you – I have not been as quiet as you may have thought.