Friend requests not showing

I've had several people tell me they've sent me friend requests that I haven't actually received. -------------No, my friends list hasn't been maxed at these times.---------------- I even sent a friend request from my main to my smurf without it appearing. I know that they're being sent, however, because returning the friend request automatically adds each other as friends. I've noticed this happening several (4-5) times in the past few weeks.

The only other information I can give is that it's possibly only when typing the name into the Add a Friend box, since I didn't meet any of these people in a previous game to be added that way.