Well, this is not a bug, but definitely an issue. When player receives the box with an item (e.g. leggings) but does not equip them, it is nearly impossible to get drop the second time. People are reporting 800+ kills and hours of farm. Worst thing here, the drop is acquired per account, not per character. So if one gets chest dropped and doesn't equip an item, this collection is good as dead for the account.
I believe first impression matters, especially now when there's a decent fresh players influx. And from my perspective this looks like a punishment or frustration at least. It is extremely easy to miss equipping phase, I can name several scenarios right away from the top of my head.
The solution I'd propose is extremely simple - let these items drop rate to be bound to the character, not to the account. At best - to the new characters. They are literally worthless, not sellable, nor reforgeable so abusing should not become an issue.