RSS not updating

For some reason my RSS feeds are not updating. I published a blog post on Sunday and my RSS has yet to update. The feed is at https://pbdigest.com/feed – the first entry is the original place holder I had in draft form… The post is at https://www.pbdigest.com/photographing-an-eclipse-filters/ – so clearly the content is there.

I don’t have any caching plugins and have tried adding something similar to:
add_filter(‘wp_feed_cache_transient_lifetime’, create_function(”, ‘return 60;’));
in my theme’s functions file with no luck.

Is there a way to force a rebuild of the RSS feed? Evidently clicking the Publish/Update buttons doesn’t appear to be working for me….

Thanks in advance for the help.