However, they have finally fixed another, far more annoying bug in the conquest point system. It's only taken 8 months. So what was the bug? Basically, you can cap out to 1800 with arena, and to get to your 2200 conquest for the week, you have to get the last 400 from a rated battleground. However, you had to do it in that order. Do a rated battleground on the day of the reset before you capped arena? Well, that will count towards your arena total of 1800. What you have to do in 5.3 is get to 1800 with arenas, and then do a rated battleground.
But, in patch 5.4, it's finally fixed. At last, you can do arenas and your one rated battleground to fully cap out conquest in any order you like. Quite why it's taken so long for this to be sorted out, I can only imagine, but I'm really glad it has been. It's so frustrating to forget about it and grab an early-week PuG for a rated battleground, not having maxed out your arena cap.