This quest isn't glitched. I've done it many times on here and it is working fine.
But sometimes the server is getting a bit crazy, this is rare though.
But however, I think I maybe able to help you:
- abandon (give up) the quest in your quest list
- take the same quest again (no worries, that single object you already got will stay in your inventory and this part of the quest will be finished already)
- now head over to Pamir Sanctuary (there are more of the purple warriors running around there) and kill those purple monsters
As I was in the same situation, a looong time ago, this is how I was able to finish the quest. After doing so and killing the purple ones at Pamir, I had the second (in my case still missing too) object within 10 minutes and was finally able to finish that quest.
Good luck!