If you ever discard a Quest Item, contact Support. If it was recently discarded (last few days), it'll show in records. If not, a quick screenshot of your Quest Log, showing you receiving the item from the quest will get it replaced.
I have sent you a replacement Viper Strike Longsword.
Hmm. That's interesting but seems like it needs to be immediately pressed. If you wait literally 1 second there's zero issue. It really needs to be instantly pressed to have this happen. Almost like it's scripted.