Guild Wars 2

Twice I’ve killed the Treasure Mushroom and twice I have received the Invisible Mushroom Spore, yet it won’t “collect” on the character that got it. Instead it collects on characters which I have never killed the Treasure Mushroom on.
I want it for my Necromancer. I don’t care about the others right now.

This isn’t a bug. The Invisible Mushroom Spore is a required item for each elite specialization’s weapon collection, and as such, it will unlock the collections in alphabetical order based on the name of the elite specialization:

Berserker
Chronomancer
Daredevil
Dragonhunter
Druid
Herald
Reaper
Scrapper
Tempest

So, for example, if you wanted to unlock the Spore for your Reaper’s weapon collection, you would have to kill 7 Treasure Mushrooms to unlock it for your greatsword collection.