Since the augmented GNB ilvl 360 weapon (Yaita Kai) dyes as it should, I assumed this is a bug on Gyosei Kai as it gives the option to dye... but nothing actually dyes when you try it.

Date & Time: 7/17/2019
Frequency: Constant
World name: Mateus
Character name: Khasar Ejinn
NPC name: E'bolaff <Gear Exchange>
Class/Level: DNC Lvl. 70 ilvl 360
Party or solo: Solo
In-game time: 6:33pm
Area and coordinates: Rhalgr's Reach, X:13,6 Y:12,2
Steps:
1. Speak to E'bolaff in Rhalgr's Reach
2. Choose option Ryumyaku Gear Augmentation (DoW)) II
3. Try On Gyosei Kai
4. Enable Dye Preview - shuffle between color options, nothing changes.