Guild Wars 2

First chests I have visited today in Queensdale are both already open.

If you opened them already, they stay opened.
You have to find new ones.

and I assume you mean on top of the balloon towers

So even if you opened them days ago they remain open now?

Yes they stay opened and you have to find new regions.
After 30 balloon towers for the achievement, all chests stay opened and cannot be looted anymore.

See, I went to Queensdale on a character and halfway up the chest opened and I got no reward. I hadn’t visited that tower before at any point or on a different character.

It’s tricky when there seem to be two problems at hand – a misunderstanding of how they work and a genuine bug.

It does appear that the two chests in Queensdale are linked and if you open one you get locked out of the other.

Thanks for the info – so much conflicting information