Sometimes the website shows an incomplete list of feed's stories

From the Unread view, I’ll click on a feed to see all of its unread stories. I’ll read them one by one until the end, then click reload - and now there’s more! They’re not new stories, they just didn’t show up the first time. This is a problem - what if I had pressed ‘mark all as read’ instead? I’d have missed them.

I think while I’m reading a feed, there should be some code running in the background to double check and fix the displayed list of stories. There should also be some visual confirmation that what I’m looking at has been double checked.

I’ve never had this problem in the android client, only the website.