First thing first:
Just DONOT use any of the memento if it’s in your bag, when you are dong a M+ dungeon.
Using the memento when you are doing a M+, it will clear the entire “Fragmented Memento of Epoch Challenges” in your bag.
I was soloing a +15 Vault of the Warden early this morning, and found an un-used memento left in my bag. The icon looks like a green book. I right clicked on the icon, and not only the memento was used, the more than 80 Fragmented Memento in my bag was gone at the same time.
It’s clearly a bug, and I’ve submitted a bug report. However, I don’t really think bliz will contact me, so I raised a ticket asking customer support if there’s any way I can get my fragmented mementos back.
Without surprise, the customer is completely useless. The guy who picked up my ticket just copied and paste a dialogs, with nothing helpful.
I tried using item recovery system (although I know it won’t help), and it only listed the items that has been scraped.
I don’t think bliz can do anything to recover my mementos, but I’m sharing the info with the whole community so that no one else will lost their memento due to the bug.
As far as I know, someone has lost more than 1000 fragmented mementos.
Hope it helps.