Thanks for the response, Brian. The most recent article, published at 4:49p EST yesterday did begin showing up 8 hours later in feed readers, around midnight (which is a longer delay than I'm used to with my Feedburner feed - it's historically been instant or close to it).
However, the next 3 most recent articles (all republished articles) on 10/10, 10/3, and 9/23 respectively are still not showing at all in feed readers, even though they are showing in the Feedburner Feed. So there seems to be some sort of miscommunication there regarding republishes.
FYI, there also seems to be an issue with images showing in feed readers.