Disc Priest Reparation buff not detected by Warcraftlogs if pre-stacked before combat?

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:

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:
(I definitely cast Penance, so must have had Reparation buff)

Reparation buff detected (I only had 99.43% uptime):