Requiescat bug in The Weapon's Refrain (Ultimate)

Date & Time: Many times starting from the release of The Weapon's Refrain (Ultimate)
Frequency: Always, under the right conditions.
World name: Hyperion
Character name: Shalice Icefrost
Retainer name: N/A
NPC name: N/A
Monster name: Titan and Ifrit (Ultimate)
Class/Level: PLD/70
Party or solo: Party
In-game time: N/A
Area and coordinates: The Weapon's Refrain (Ultimate) x 6.0 / y 6.0
Housing: N/A

Paladin's job ability "Requiescat" goes on cooldown but the effect isn't granted under specific conditions and timings.

When:

1. If you cast Requiescat exactly when Titan's Earthen Fury animation is casting, in The Weapon's Refrain (Ultimate)
2. If you cast Requiescat exactly when Ifrit's Eruptions are exploding, in The Weapon's Refrain (Ultimate)
3. This happens 100% of the time if you do it in those specific times. I have not tested them in other difficulties of these primals. I also have not experienced this issue in other parts of the fight.
4. If you do it slightly earlier or after the mentioned animations, there is no problem
5. It's not a visual bug, the effect of the ability is not granted (no +dmg for Holy Spirit), but the ability goes on cooldown.

Salutations, Shalice Icefrost!

Thank you for your patience while your concern was being investigated, and we apologize for any inconvenience this has caused you. In order to continue on with the investigation, the development team would like more details about MP% that you were at when you initiated Requiescat. Once we have those details, we will make sure to escalate your information to the development team to continue reviewing this concern. Thanks again for your patience and understanding!

FINAL FANTASY XIV Support Team