Attacking an NPC when it becomes part of a FATE prevents it from aggro'ing

Attacking an NPC the moment it becomes part of a FATE prevents the NPC from becoming aggressive. This is strange because the NPC will also never reset and instead walk around with missing health.

Date & Time: 02/24/2022 5:30am PST
Frequency: Always
World name: Adamantoise
Character name: Lulu Pillow
Retainer name: ---
NPC name: ---
Monster name: Shelfclaw Reaver
Class/Level: ---
Party or solo: ---
In-game time: ---
Area and coordinates: ---
Housing: ---

Steps:
I assume other FATEs would work, but Watch Your Tongue with Shelfclaw Reavers are easy to reproduce with.

1. Attack (without killing) a Shelfclaw Reaver and stop attacking
2. The FATE Watch Your Tongue spawns immediately
3. Shelfclaw Reaver becomes part of the FATE