Open Letters

I can't finish Achievement:Open Letters,I can't get 'Hidden Letter: Prosperity' from the supply crate near 'Zirh the Venomous' , when I click on it it says:I'll stake the area out and get to the bottom of it, I researched the web and 1 site told me to finish:Out of the shadows Mastery,else I couldn't finish Open Letters, so I finished it today but no progress in Open Letters same story like I said before, they say also that I needed a finished Living World Season 3 and thats what I have,further I couldn't find any info,so what am I doing wrong? they're not saying that I need: Shining Blade Bounty Notice: Zirh the Venomous, but I'm thinking about it and could this be the solution?I'm harvesting encoded orders right now from normal bandits but it can take a while to obtain Zirh the Venomous cuz it's random when you go to: Shining Blade Officer Raglan, would be a nice shortcut if someone knows it

Is it a possibility that I need:Shining Blade Bounty Notice: Zirh the Venomous?

The requirements from what I've read are as follow:

• A character Must have Completed Chapter 1, 2 or3 of Season 3 (not the whole season)
• The items can only be interacted with a "Character" that has done that (this is whats probably messing you up)
• You need a Shining Blade Bounty Notice of the bandit to get the hidden letter.

I can't find anything that says you have to fight the bandit, but that might be a requirement as well. They're all on 10min respawn timers, so its just a matter of waiting.