I noticed that sometimes the Disc Priest buff Reparation (Priest T18 Discipline 2P Bonus) cannot be found at all in some of my logs. When searching Google, I came across this post:
http://webcache.googleusercontent.com/search?q=cache:GFgKtY0uNYgJ:us.battle.net/wow/en/forum/topic/20043424683+&cd=1&hl=en&ct=clnk&gl=us
There is a bug in Warcraftlogs. I encounter it myself frequently.
Scenario: When you pre-stack the reparation buff up to 6 and keep it all throughout the fight (never let it drop), it doesn’t appear as one of your buffs at all.
I definitely do pre-stack reparation to 6 stacks before combat.
Looking at my logs last night, this theory might be correct.
No Reparation buff detected:
https://www.warcraftlogs.com/reports/GZH8rkLKpzf3yRvF#fight=28&type=auras&source=30
(I definitely cast Penance, so must have had Reparation buff)
Reparation buff detected (I only had 99.43% uptime):
https://www.warcraftlogs.com/reports/GZH8rkLKpzf3yRvF#fight=6&type=auras&source=30