I got a gold Antitiquies lead drop from the Charging station boss, but now when I go into the list of leads, its not there anymore, are gold ones timed or something?
How about this, ZOS please include a timer for each lead to show how much time a player has before it expires. Such as a count down. I think this small communication will help reduce a lot of frustration. Copy and edit some of the code from the guild store listings countdown and mod it for this stuff.
It sounds like it was a lead you already had done for your mount or other multi part antiquity. They keep dropping even after you dig them up. You'll see the lead in the loot, but the game won't allow you to dig it again if you already have it. For mythic items and the music box, you'll have to complete the entire item before being able to reacquire leads and for the mount, the game keeps giving you the lead, even though it won't let you dig it up again.