I picked up/purchased an item but it just disappeared, where did it go?

In Arkheron, your team can only carry one of each named item, or Relic, and any other copies will upgrade those Relics. Each Eternal Relic can only be upgraded to level 3.

If a Relic is glowing orange on the floor, it means that one of your teammates is currently carrying it, and picking it up will upgrade the Relic for them. If your teammate is carrying a Relic and you purchase the same one at the Shrine, it will result in an upgrade for your teammate rather than providing you with that Relic.