I’ve recently noticed that my friend list mismatches the number of online people. As in the image below shows the friend icon from the top right corner shows a 3 while the opened friend list only shows 1 active friend.
Occasionally my friendslist stats that I have 1 more friend online than I currently do. This is at seemingly random times, although it may have decided someone is my friend, but not put them on my list, so it shows their number on the green icon, but doesn’t show them on my friends list. This has been happening since I joined this site, in September, and even happened before I had added any friends. (It occasionally showed a 1, instead of zero, and displayed an empty list.