So this has been happening for about 3 months now, there’s posts in arena and BG forums, the scoreboard occasionally only shows HKs/Deaths, nothing else, like Damage/Healing/etc.
You can fix by doing /reload, but that’s annoying, especially if you’re in the middle of the BG, or if you have a lot of addons, and if you do a lot of PvP. This started on the patch previous to 10.1.5.
I could not find any posts in bug forums recently that related to it.
https://imgur.com/a/ELpWrDW