Clicking "Show More" in a User Profile Activity Stream Only Shows 1 Additional Activity

I was looking at the user profile activity stream for [Helper] Mark Derickson and at one point in the activity stream I noticed that when I clicked "Show More" I appeared to be at the place where I usually am when I click it. However I noticed it appeared to have added 1 activity and it just scrolled me up. After a few more times clicking show more it started working normally again.