The "Load More Submissions" button seems to be working now! :D

Update: After clearing all submissions from What's New, I have stopped seeing this bug.

I had around 4,000 notifications in "What's New" when I saw this bug. I gave up on trying to go through all of them and just hit Clear All. Since then I've had about 200 new submissions in What's New and was not able to replicate this bug when clearing them.

I can confirm that the "Load more submissions" button does not work. I have to scroll down to get more submissions to load. I am using Firefox.