Dear ExperienceRO,
I checked and they work! They spawn! So if anyone have been telling you they don't, it's either:
1. They're spreading a propaganda.
2. They didn't want to pay the guild member(s) who conquered the Castle(s) for them.
3. They want to hoard the loots for themselves.
SO yes... I checked and I'm sure...
Chests spawn everyday at 7:01 am (server time)...
Enjoy and bai...
Jac