I have been next to the chest and gotten nothing (not even Grade 5 Dark Matter ; ; ). So it is possible to get nothing. And if you are far away from chest, yes, you will see nothing and get nothing and wonder if anyone opened the chest ^.^;. That is an unfortunate and I hope it is fixed in future.

Not sure what 'etiquette' is, but to me, it is more fun for all us adventurers to stand around the chest and open it together, as we all earned it together.

Now, some people believe /grovel /bow and (soon: /pray) are the magic emotes that increase the chance of a drop. But this is all hog-wash, as everyone knows its all about direction and having a taru dancing whilst opening it that increases the drop rate.

Good luck in there ^.^