Missing items happen all the time. If you are looking to recover one you will need to report it immediately. If you deleted the item you most likely cannot get it back.
The issue and preferred resolution, in GetHuman-ballista's own words:
I recently purchased a few PUBG Early Bird Keys, all of which had the usual *-day waiting period before becoming tradable and marketable. After the * days however, the keys all became marketable but none of them are tradable. Is this a bug that you can fix?
I trust that Steam Software will make this right and come up with a resolution that is fair.
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