RSS feed not showing new posts

Hi all! I’m having a problem with my RSS feed that’s really making me want to pull my hair out.

If I look at my feed in my browser https://www.routetoretire.com/feed/, all my posts are listed.

However, if I look at the feed in any RSS reader, the latest post it will show is from 8/12/15. As of now, I have an additional 8 posts that were created after that, but they don’t show up.

If I check it https://validator.w3.org/feed/check.cgi?url=http%3A//www.routetoretire.com/feed/, I get “Feeds should not be served with the “text/html” media type”. That is after I was getting a
“Your feed appears to be encoded as “UTF-8”, but your server is reporting “US-ASCII” error. So I added “AddDefaultCharset UTF-8” to the .htaccess.

I see some things referring to modifying content in wp-rss2.php, but I don’t seem to see that file anywhere.

I’ve been trying to figure this out for a week and I’m at a loss. Any help would be truly appreciated!

Thanks,

— Jim