[Plugin: WP RSS Aggregator] not showing new posts?

I have it running on https://www.wpmayor.com/wordpress-news/ to make sure the latest version is working well, as you can see it is updating well there.

Now for your issue, provided the feeds are working well, please check if you have any caching plugins enabled, they might be caching the page and thus not showing the updated feeds.

You can also use the feeds on the WPMayor site to try and replicate that example, as those feeds are working for sure.